<?xml version="1.0" encoding="ISO-8859-7" standalone="no"?>
<!--
Ôï Åã÷åéñßäéï ôïõ FreeBSD: Ï Äéá÷åéñéóôÞò Ôüìùí Vinum
ÃñÜöôçêå áðü ôïí:
Greg Lehey (grog at lemis dot com)
Åíóùìáôþèçêå óôï Åã÷åéñßäéï ôïõ FreeBSD áðü ôïõò:
Hiten Pandya <hmp@FreeBSD.org>
Tom Rhodes <trhodes@FreeBSD.org>
$FreeBSD$
%SOURCE% en_US.ISO8859-1/books/handbook/vinum/chapter.sgml
%SRCID% 38826
-->
<chapter id="vinum-vinum">
<chapterinfo>
<authorgroup>
<author>
<firstname>Greg</firstname>
<surname>Lehey</surname>
<contrib>Áñ÷éêÞ óõíåéóöïñÜ ôïõ </contrib>
</author>
</authorgroup>
</chapterinfo>
<title>Ï Äéá÷åéñéóôÞò Ôüìùí Vinum</title>
<sect1 id="vinum-synopsis">
<title>Óýíïøç</title>
<para>ÏôéäÞðïôå äßóêïõò êáé áí Ý÷åôå, ðÜíôá õðÜñ÷ïõí ðéèáíÜ
ðñïâëÞìáôá:</para>
<itemizedlist>
<listitem>
<para>Ìðïñåß íá åßíáé ðïëý ìéêñïß.</para>
</listitem>
<listitem>
<para>Ìðïñåß íá åßíáé ðïëý áñãïß.</para>
</listitem>
<listitem>
<para>Ìðïñåß íá ìçí åßíáé áñêåôÜ áîéüðéóôïé.</para>
</listitem>
</itemizedlist>
<para>Ãéá ôá ðñïâëÞìáôá áõôÜ, Ý÷ïõí ðñïôáèåß êáé õëïðïéçèåß äéÜöïñåò
ëýóåéò. ¸íáò óõ÷íÜ ÷ñçóéìïðïéïýìåíïò ôñüðïò ðñïóôáóßáò, åßíáé ìå ôçí
÷ñÞóç ðïëëáðëþí êáé ïñéóìÝíåò öïñÝò ðåñéôôþí (redundant) äßóêùí. Åêôüò
áðü ôçí õðïóôÞñéîç ðïõ ðáñÝ÷åôáé ãéá óõóêåõÝò (êÜñôåò êáé åëåãêôÝò)
hardware RAID, ôï âáóéêü óýóôçìá ôïõ &os; ðåñéëáìâÜíåé ôï äéá÷åéñéóôÞ
ôüìùí (volume manager) Vinum, Ýíá ðñüãñáììá ïäÞãçóçò ôýðïõ
ìðëïê ôï ïðïßï õëïðïéåß åéêïíéêïýò äßóêïõò.
Ôï <emphasis>Vinum</emphasis> áðïêáëåßôáé êáé
<emphasis>Äéá÷åéñéóôÞò Ôüìùí</emphasis>, êáé åßíáé Ýíáò ïäçãüò
åéêïíéêþí äßóêùí ðïõ áíôéìåôùðßæåé ôá ðáñáðÜíù ôñßá ðñïâëÞìáôá.
Ôï Vinum ðáñÝ÷åé êáëýôåñç åõåëéîßá, áðüäïóç êáé áîéïðéóôßá óå ó÷Ýóç ìå
ôá ðáñáäïóéáêÜ óõóôÞìáôá áðïèÞêåõóçò, êáé õëïðïéåß ôá ìïíôÝëá RAID-0,
RAID-1 êáé RAID-5, ôüóï ìåìïíùìÝíá, üóï êáé óå óõíäõáóìü ìåôáîý
ôïõò.</para>
<para>Ôï êåöÜëáéï áõôü ðáñÝ÷åé ìéá åðéóêüðçóç ôùí ðéèáíþí ðñïâëçìÜôùí ôùí
ðáñáäïóéáêþí óõóôçìÜôùí áðïèÞêåõóçò, êáé ìéá åéóáãùãÞ óôï Äéá÷åéñéóôÞ
Ôüìùí Vinum.</para>
<note>
<para>Îåêéíþíôáò áðü ôï &os; 5 êáé ìåôÜ, ôï Vinum îáíáãñÜöôçêå
þóôå íá åíóùìáôùèåß óôçí áñ÷éôåêôïíéêÞ GEOM (<xref linkend="GEOM"/>),
äéáôçñþíôáò ùóôüóï ôéò áñ÷éêÝò éäÝåò, ïñïëïãßá, êáé ôç ìïñöÞ ôùí
ìåôá-äåäïìÝíùí (metadata) ðïõ áðïèçêåýïíôáé óôïí äßóêï.
Ç íÝá áõôÞ åêäï÷Þ ïíïìÜæåôáé <emphasis>gvinum</emphasis> (áðü ôï
<emphasis>GEOM vinum</emphasis>). Ôï áêüëïõèï êåßìåíï áíáöÝñåôáé
óõíÞèùò óôï <emphasis>Vinum</emphasis> ùò áöçñçìÝíç Ýííïéá, Üó÷åôá ìå
ôéò ëåðôïìÝñåéåò ôçò õëïðïßçóçò. ¼ëåò ïé åíôïëÝò èá ðñÝðåé ôþñá íá
êáëïýíôáé ìå ôç ÷ñÞóç ôçò <command>gvinum</command>,
ôï Üñèñùìá ðõñÞíá (kernel module) Ý÷åé ìåôïíïìáóôåß óå
<filename>geom_vinum.ko</filename> áðü <filename>vinum.ko</filename>,
êáé üëá ôá áñ÷åßá óõóêåõþí âñßóêïíôáé óôïí êáôÜëïãï
<filename class="directory">/dev/gvinum</filename> áíôß ãéá
<filename class="directory">/dev/vinum</filename>. Áðü ôï
&os; 6 êáé ìåôÜ, ç ðáëéÜ õëïðïßçóç ôïõ Vinum äåí ðåñéëáìâÜíåôáé
ðëÝïí óôï âáóéêü óýóôçìá.</para>
</note>
</sect1>
<sect1 id="vinum-intro">
<title>Ïé Äßóêïé Åßíáé Ðïëý Ìéêñïß</title>
<indexterm><primary>Vinum</primary></indexterm>
<indexterm><primary>RAID</primary>
<secondary>software</secondary></indexterm>
<para>Ïé äßóêïé ãßíïíôáé ïëïÝíá êáé ìåãáëýôåñïé, áëëÜ ìå ôïí ßäéï ñõèìü
áõîÜíïíôáé åðßóçò êáé ïé áðáéôÞóåéò ìáò óå áðïèçêåõôéêü ÷þñï. ÐïëëÝò
öïñÝò èá âñåèåßôå óå èÝóç íá ÷ñåéÜæåóôå Ýíá óýóôçìá áñ÷åßùí ìåãáëýôåñï
áðü ôïõò äßóêïõò ðïõ Ý÷åôå äéáèÝóéìïõò. Óßãïõñá ôï ðñüâëçìá áõôü äåí
åßíáé ôüóï Ýíôïíï üóï ðñéí äÝêá ÷ñüíéá, áëëÜ åîáêïëïõèåß íá õðÜñ÷åé.
ÌåñéêÜ óõóôÞìáôá åðéëýïõí áõôü ôï ðñüâëçìá, äçìéïõñãþíôáò ìéá åéêïíéêÞ
óõóêåõÞ ðïõ áðïèçêåýåé ôá äåäïìÝíá óå Ýíá áñéèìü äéáêñéôþí
äßóêùí.</para>
</sect1>
<sect1 id="vinum-access-bottlenecks">
<title>ÊáèõóôåñÞóåéò Ðñüóâáóçò</title>
<para>Óôá ìïíôÝñíá óõóôÞìáôá, õðÜñ÷åé óõ÷íÜ áíÜãêç ðñüóâáóçò äåäïìÝíùí
áðü ðïëëÝò äéåñãáóßåò ôáõôü÷ñïíá. Ãéá ðáñÜäåéãìá, ìåãÜëïé åîõðçñåôçôÝò
FTP Þ HTTP ìðïñåß íá Ý÷ïõí áíÜ ðÜóá óôéãìÞ ÷éëéÜäåò ôáõôü÷ñïíåò
åîùôåñéêÝò óõíäÝóåéò êáé íá äéáèÝôïõí ðïëëáðëÝò äéåðáöÝò 100 Mbit/s
ïé ïðïßåò îåðåñíÜíå êáôÜ ðïëý ôéò äõíáôüôçôåò ìåôáöïñÜò äåäïìÝíùí ôùí
ðåñéóóüôåñùí óêëçñþí äßóêùí.</para>
<para>Ôá ôñÝ÷ïíôá ìïíôÝëá óêëçñþí äßóêùí ìðïñïýí íá ìåôáöÝñïõí äåäïìÝíá
óåéñéáêÜ ìå ôá÷ýôçôá ìÝ÷ñé êáé 70 MB/s, áëëÜ ç ôéìÞ áõôÞ Ý÷åé ìéêñÞ
óçìáóßá óå Ýíá ðåñéâÜëëïí üðïõ ðïëëÝò áíåîÜñôçôåò äéåñãáóßåò ÷ñåéÜæïíôáé
ðñüóâáóç óôïí ßäéï äßóêï. Óå ôÝôïéåò ðåñéðôþóåéò, êÜèå äéåñãáóßá ìðïñåß
íá åðéôý÷åé ìüíï Ýíá ìéêñü ðïóïóôü ôçò ìÝãéóôçò áõôÞò áðüäïóçò. Åßíáé
ðéï åíäéáöÝñïí íá äïýìå ôï ðñüâëçìá áðü ôçí ðëåõñÜ ôïõ õðïóõóôÞìáôïò
äßóêùí: ï óçìáíôéêüò ðáñÜãïíôáò åßíáé ï öüñôïò óôïí ïðïßï õðïâÜëëåôáé
ôï õðïóýóôçìá êáôÜ ôç äéÜñêåéá ìéáò ìåôáöïñÜò. Ìå Üëëá ëüãéá, ï ÷ñüíïò
ðïõ ðáñáìÝíïõí áðáó÷ïëçìÝíïé ïé äßóêïé åîáéôßáò ôçò ìåôáöïñÜò.</para>
<para>Óå êÜèå ìåôáöïñÜ äåäïìÝíùí, ï äßóêïò èá ðñÝðåé ðñþôá íá ôïðïèåôÞóåé
ôéò êåöáëÝò óôï óùóôü óçìåßï, íá ðåñéìÝíåé íá ðåñÜóåé ï ðñþôïò ôïìÝáò
êÜôù áðü ôçí êåöáëÞ áíÜãíùóçò, êáé Ýðåéôá íá åêôåëÝóåé ôç ìåôáöïñÜ.
Ïé åíÝñãåéåò áõôÝò ìðïñïýí íá èåùñçèïýí áôïìéêÝò: äåí Ý÷åé íüçìá íá
ðñïóðáèÞóïõìå íá ôéò äéáêüøïõìå.</para>
<para><anchor id="vinum-latency"/> Áò èåùñÞóïõìå ìéá ôõðéêÞ ìåôáöïñÜ
ðåñßðïõ 10 kB. Ç ôñÝ÷ïõóá ãåíéÜ äßóêùí õøçëÞò áðüäïóçò ìðïñåß íá
ôïðïèåôÞóåé ôéò êåöáëÝò óôç óùóôÞ èÝóç óå ðåñßðïõ 3.5 ms. Ïé ðéï
ãñÞãïñïé äßóêïé Ý÷ïõí ôá÷ýôçôá ðåñéóôñïöÞò 15.000 óôñïöÝò ôï ëåðôü,
Ýôóé ï ìÝóïò ÷ñüíïò êáèõóôÝñçóçò ðåñéóôñïöÞò (ìéóÞ ðåñéóôñïöÞ) åßíáé
2 ms. Ìå 70 MB/s, ç ìåôáöïñÜ áõôÞ êáè' áõôÞ èá ÷ñåéáóôåß
ðåñßðïõ 150 μs, ó÷åäüí ôßðïôá óå ó÷Ýóç ìå ôï ÷ñüíï ðïõ
÷ñåéÜæåôáé ãéá ôçí ôïðïèÝôçóç ôçò êåöáëÞò óôï óùóôü óçìåßï.
Óôçí ðåñßðôùóç áõôÞ, ï ðñáãìáôéêüò ñõèìüò ìåôáöïñÜò ðÝöôåé óå ëßãï
ðåñéóóüôåñï áðü Ýíá 1 ÌÂ/s êáé åßíáé åìöáíÝò üôé åîáñôÜôáé óå
ìåãÜëï âáèìü áðü ôï ìÝãåèïò ôùí äåäïìÝíùí ðïõ ìåôáöÝñïíôáé.</para>
<para>Ç ðáñáäïóéáêÞ êáé ðñïöáíÞò ëýóç óå áõôü ôï ðñüâëçìá, åßíáé íá
ðñïóèÝóïõìå <quote>ðåñéóóüôåñïõò äßóêïõò</quote>: áíôß íá
÷ñçóéìïðïéÞóïõìå Ýíá ìåãÜëï äßóêï, íá âÜëïõìå ðïëëïýò ìéêñüôåñïõò ìå
ôïí ßäéï ôåëéêü áðïèçêåõôéêü ÷þñï. ÊÜèå äßóêïò Ý÷åé äõíáôüôçôá íá
ìåôáêéíåß ôéò êåöáëÝò êáé íá ìåôáöÝñåé äåäïìÝíá áíåîÜñôçôá áðü ôïõò
Üëëïõò, Ýôóé ç ðñáãìáôéêÞ äéáìåôáãùãÞ áõîÜíåé áíáëïãéêÜ ìå ôï ðëÞèïò
ôùí äßóêùí ðïõ ÷ñçóéìïðïéïýíôáé.</para>
<para>Ç ðñáãìáôéêÞ áýîçóç ôçò äéáìåôáãùãÞò åßíáé öõóéêÜ ìéêñüôåñç áðü ôï
ðëÞèïò ôùí äßóêùí ðïõ ÷ñçóéìïðïéïýíôáé: áí êáé êÜèå äßóêïò åßíáé éêáíüò
íá ìåôáöÝñåé äåäïìÝíá ðáñÜëëçëá ìå ôïõò Üëëïõò, äåí õðÜñ÷åé ôñüðïò íá
åîáóöáëßóïõìå üôé ïé áéôÞóåéò ìåôáöïñÜò êáôáíÝìïíôáé ïìïéüìïñöá óå üëïõò
ôïõò äßóêïõò. Åßíáé áíáðüöåõêôï üôé ôï öïñôßï óå Ýíá äßóêï èá åßíáé
ìåãáëýôåñï áðü ôï öïñôßï óå êÜðïéï Üëëï.</para>
<indexterm>
<primary>disk concatenation</primary>
</indexterm>
<indexterm>
<primary>Vinum</primary>
<secondary>concatenation</secondary>
</indexterm>
<para>Ç ïìïéïìïñößá êáôáíïìÞò ôïõ öïñôßïõ óôïõò äßóêïõò, åîáñôÜôáé óå
ìåãÜëï âáèìü áðü ôïí ôñüðï ðïõ Ý÷ïõí ìïéñáóôåß ôá äåäïìÝíá óå áõôïýò.
Óôçí ðáñáêÜôù óõæÞôçóç, åßíáé âïëéêü íá óêåöôüìáóôå ôïí áðïèçêåõôéêü
÷þñï åíüò äßóêïõ ùò Ýíá ìåãÜëï áñéèìü áðü ôïìåßò óôïõò ïðïßïõò Ý÷ïõìå
ðñüóâáóç ìå âÜóç Ýíá áñéèìü, áêñéâþò üðùò ïé óåëßäåò óå Ýíá âéâëßï.
Ç ðéï ðñïöáíÞò ìÝèïäïò åßíáé íá ÷ùñßóïõìå ôïí åéêïíéêü äßóêï óå ïìÜäåò
áðü óõíå÷üìåíïõò ôïìåßò, üðïõ êáèåìßá Ý÷åé ôï ìÝãåèïò ôïõ ðñáãìáôéêïý
áíåîÜñôçôïõ öõóéêïý äßóêïõ, êáé íá ôéò áðïèçêåýóïõìå ìå áõôü ôïí ôñüðï,
ðåñßðïõ óáí íá ðáßñíáìå Ýíá ìåãÜëï âéâëßï êáé íá ôï ÷ùñßæáìå óå
ìéêñüôåñïõò ôüìïõò. Ç ìÝèïäïò áõôÞ ïíïìÜæåôáé
<emphasis>óõíÝíùóç (concatenation)</emphasis> êáé Ý÷åé ôï ðëåïíÝêôçìá
üôé äåí áðáéôåß ôá ìåãÝèç ôùí äßóêùí íá Ý÷ïõí êÜðïéá ó÷Ýóç ìåôáîý ôïõò.
Ëåéôïõñãåß ðïëý êáëÜ üôáí ç ðñüóâáóç óôïí åéêïíéêü äßóêï åßíáé
ïìïéüìïñöá êáôáíåìçìÝíç óå üëç ôçí ðåñéï÷Þ äéåõèýíóåùí ôïõ. ¼ôáí ç
ðñüóâáóç óõãêåíôñþíåôáé óå ìéá ìéêñüôåñç ðåñéï÷Þ, ç âåëôßùóç åßíáé
ìéêñüôåñç. Ôï <xref linkend="vinum-concat"/> äåß÷íåé ôçí áêïëïõèßá ìå
ôçí ïðïßá ãßíåôáé ç êáôáíïìÞ ôùí èÝóåùí áðïèÞêåõóçò üôáí
÷ñçóéìïðïéåßôáé ç óõíÝíùóç.</para>
<para>
<figure id="vinum-concat">
<title>ÏñãÜíùóç ÓõíÝíùóçò</title>
<graphic fileref="vinum/vinum-concat"/>
</figure>
</para>
<indexterm>
<primary>disk striping</primary>
</indexterm>
<indexterm>
<primary>Vinum</primary>
<secondary>striping</secondary>
</indexterm>
<indexterm>
<primary>RAID</primary>
</indexterm>
<para>¸íáò åíáëëáêôéêüò ôñüðïò áðïèÞêåõóçò, åßíáé íá ÷ùñéóôåß ç ðåñéï÷Þ
äéåõèýíóåùí óå ìéêñüôåñá ôìÞìáôá ßóïõ ìåãÝèïõò ôá ïðïßá íá áðïèçêåýïíôáé
óåéñéáêÜ óå äéáöïñåôéêÝò óõóêåõÝò. Ãéá ðáñÜäåéãìá, ïé ðñþôïé 256 ôïìåßò
ìðïñåß íá åßíáé áðïèçêåõìÝíïé óôïí ðñþôï äßóêï, ïé åðüìåíïé 256 óôïí
åðüìåíï äßóêï, ê.ï.ê. ÌåôÜ ôçí ÷ñÞóç êáé ôïõ ôåëåõôáßïõ äßóêïõ,
ç äéáäéêáóßá åðáíáëáìâÜíåôáé ìÝ÷ñé íá ãåìßóïõí üëïé ïé äßóêïé. ÁõôÞ
ç ìÝèïäïò ïíïìÜæåôáé <emphasis>striping</emphasis> Þ
<acronym>RAID-0</acronym>.
<footnote>
<para>Ôï <acronym>RAID</acronym> óçìáßíåé <emphasis>Redundant
Array of Inexpensive Disks</emphasis> êáé ðáñÝ÷åé äéÜöïñåò ìïñöÝò
áíï÷Þò óå óöÜëìáôá, áí êáé óôçí ðáñáðÜíù ÷ñÞóç ï üñïò åßíáé
êÜðùò ðáñáðëáíçôéêüò: ôï <acronym>RAID-0</acronym> äåí ðáñÝ÷åé êáìéÜ
ôÝôïéá ðñïóôáóßá äåäïìÝíùí.</para>
</footnote>
Ôï striping áðáéôåß êÜðùò ðåñéóóüôåñç ðñïóðÜèåéá ãéá ôïí åíôïðéóìü ôùí
äåäïìÝíùí êáé ìðïñåß íá ðñïêáëÝóåé ìåãáëýôåñï öïñôßï I/O üôáí ìéá
ìåôáöïñÜ êáôáíÝìåôáé óå ðïëëáðëïýò äßóêïõò, áëëÜ áðü ôçí Üëëç
åðéôõã÷Üíåé ìåãáëýôåñï óôáèåñü öïñôßï óå êÜèå äßóêï.
Ôï <xref linkend="vinum-striped"/> äåß÷íåé ôç óåéñÜ ìå ôçí ïðïßá
÷ñçóéìïðïéïýíôáé ïé ìïíÜäåò áðïèÞêåõóçò óå ìéá ïñãÜíùóç ôýðïõ
stripe.</para>
<para>
<figure id="vinum-striped">
<title>Striped Organization</title>
<graphic fileref="vinum/vinum-striped"/>
</figure>
</para>
</sect1>
<sect1 id="vinum-data-integrity">
<title>Áêåñáéüôçôá ÄåäïìÝíùí</title>
<para>Ôï ôåëåõôáßï ðñüâëçìá ìå ôçí ôñÝ÷ïõóá ôå÷íïëïãßá äßóêùí, åßíáé
ç áíáîéïðéóôßá ôïõò. Áí êáé ôá ôåëåõôáßá ÷ñüíéá ç áîéïðéóôßá ôùí
äßóêùí Ý÷åé áõîçèåß óçìáíôéêÜ, åîáêïëïõèïýí íá åßíáé ôï åîÜñôçìá ìå
ôï ìåãáëýôåñï ñõèìü áðïôõ÷ßáò óôïõò åîõðçñåôçôÝò. ¼ôáí áðïôý÷åé Ýíáò
äßóêïò, ôá áðïôåëÝóìáôá ìðïñåß íá åßíáé êáôáóôñïöéêÜ: ç áíôéêáôÜóôáóç
åíüò ÷áëáóìÝíïõ äßóêïõ êáé ç áíôéãñáöÞ ôùí äåäïìÝíùí óôï íÝï ìðïñåß
íá äéáñêÝóåé ìÝñåò.</para>
<indexterm>
<primary>disk mirroring</primary>
</indexterm>
<indexterm>
<primary>Vinum</primary>
<secondary>mirroring</secondary>
</indexterm>
<indexterm>
<primary>RAID-1</primary>
</indexterm>
<para>Ï ðáñáäïóéáêüò ôñüðïò áíôéìåôþðéóçò áõôïý ôïõ ðñïâëÞìáôïò åßíáé ôï
<emphasis>mirroring</emphasis> (êáèñåðôéóìüò), ç äéáôÞñçóç äçëáäÞ äýï
áíôéãñÜöùí ôùí äåäïìÝíùí óå äéáöïñåôéêïýò äßóêïõò. Ìå ôçí åöåýñåóç ôùí
äéÜöïñùí åðéðÝäùí <acronym>RAID</acronym>, ç ôå÷íéêÞ áõôÞ Ýãéíå åðßóçò
ãíùóôÞ ìå ôçí ïíïìáóßá <acronym>RAID åðéðÝäïõ 1</acronym> Þ áðëþò
<acronym>RAID-1</acronym>. ÊÜèå åããñáöÞ óôïí ôüìï ãßíåôáé êáé óôïõò
äýï äßóêïõò. Ç áíÜãíùóç ìðïñåß íá ãßíåé áðü ïðïéïäÞðïôå äßóêï, Ýôóé
áí Ýíáò áðü ôïõò äýï áðïôý÷åé, ôá äåäïìÝíá åîáêïëïõèïýí íá åßíáé
äéáèÝóéìá óôïí Üëëï.</para>
<para>Ôï mirroring Ý÷åé äýï ðñïâëÞìáôá:</para>
<itemizedlist>
<listitem>
<para>Ôï êüóôïò. Áðáéôåß äéðëÜóéï êüóôïò áðü ïðïéáäÞðïôå ëýóç äåí
ðñïóöÝñåé áõôÞ ôç ëåéôïõñãßá.</para>
</listitem>
<listitem>
<para>Ôç ìåßùóç ôçò áðüäïóçò. Ïé åããñáöÝò ðñÝðåé íá
ãßíïíôáé êáé óôïõò äýï äßóêïõò, êáôáíáëþíïíôáò Ýôóé ôï äéðëÜóéï
åýñïò æþíçò óå ó÷Ýóç ìå Ýíá ôüìï ðïõ äåí ÷ñçóéìïðïéåß mirror.
Ç áíÜãíùóç äåí õðïöÝñåé áðü ôï ßäéï ðñüâëçìá. ÌÜëéóôá öáßíåôáé
íá åßíáé êáé ãñçãïñüôåñç.</para>
</listitem>
</itemizedlist>
<para><indexterm><primary>RAID-5</primary></indexterm>Ìéá åíáëëáêôéêÞ
ëýóç åßíáé ôï <emphasis>parity</emphasis> (éóïôéìßá), ôï ïðïßï
õëïðïéåßôáé óôá åðßðåäá 2, 3, 4 êáé 5 ôïõ <acronym>RAID</acronym>.
Áðü ôá åðßðåäá áõôÜ, ôï <acronym>RAID-5</acronym> åßíáé ôï ðéï
åíäéáöÝñïí. Ï ôñüðïò ðïõ õëïðïéåßôáé óôï Vinum, åßíáé ìéá ðáñáëëáãÞ
ôçò ïñãÜíùóçò äåäïìÝíùí ðïõ ÷ñçóéìïðïéåßôáé óôï stripe, ìå ôç äéáöïñÜ
üôé Ýíá ìðëïê áðü êÜèå stripe ÷ñçóéìïðïéåßôáé ãéá íá áðïèçêåýåé ôçí
éóïôéìßá åíüò Üëëïõ ìðëïê. Óôï Vinum, ìéá óõóôïé÷ßá
<acronym>RAID-5</acronym>, åßíáé ðáñüìïéá ìå ìéá óõóôïé÷ßá stripe,
åêôüò áðü ôï ãåãïíüò üôé õëïðïéåß <acronym>RAID-5</acronym> êáèþò êÜèå
stripe ðåñéÝ÷åé êáé ìðëïê éóïôéìßáò. Ç ôïðïèåóßá ôïõ ìðëïê éóïôéìßáò,
áëëÜæåé áðü ôï Ýíá stripe óôï åðüìåíï, êÜôé ðïõ áðáéôåßôáé áðü ôï
<acronym>RAID-5</acronym>. Ïé áñéèìïß óôá ìðëïê äåäïìÝíùí áíáöÝñïíôáé
óôç ó÷åôéêÞ áñßèìçóç ôïõò.</para>
<para>
<figure id="vinum-raid5-org">
<title>RAID-5 Organization</title>
<graphic fileref="vinum/vinum-raid5-org"/>
</figure>
</para>
<para>Óå óýãêñéóç ìå ôï mirror, ôï <acronym>RAID-5</acronym> Ý÷åé ôï
ðëåïíÝêôçìá íá áðáéôåß óçìáíôéêÜ ëéãüôåñï ÷þñï áðïèÞêåõóçò. Ç ôá÷ýôçôá
áíÜãíùóçò åßíáé ßäéá ìå ôï stripe, áëëÜ ç åããñáöÞ åßíáé óçìáíôéêÜ ðéï
áñãÞ, ðåñßðïõ ôï 25% ôçò áðüäïóçò êáôÜ ôçí áíÜãíùóç. Áí Ýíáò äßóêïò
÷áëÜóåé, ç óõóôïé÷ßá åîáêïëïõèåß íá ëåéôïõñãåß óå åëáôôùìÝíç (degraded)
êáôÜóôáóç: ç áíÜãíùóç áðü ôïõò äßóêïõò ðïõ ëåéôïõñãïýí êáíïíéêÜ
óõíå÷ßæåôáé áðñïâëçìÜôéóôá, áëëÜ ç áíÜãíùóç äåäïìÝíùí ðïõ âñßóêïíôáí
óôïí ðñïâëçìáôéêü äßóêï ðñÝðåé íá åðáíáûðïëïãéóôåß ìå âÜóç ôá
áíôßóôïé÷á ìðëïê éóïôéìßáò ðïõ âñßóêïíôáé óå üëïõò ôïõò Üëëïõò
äßóêïõò.</para>
</sect1>
<sect1 id="vinum-objects">
<title>Áíôéêåßìåíá ôïõ Vinum</title>
<para>Ãéá ôçí áíôéìåôþðéóç ôùí ðáñáðÜíù ðñïâëçìÜôùí, ôï Vinum õëïðïéåß ìéá
éåñáñ÷ßá áíôéêåéìÝíùí ôåóóÜñùí åðéðÝäùí:</para>
<itemizedlist>
<listitem>
<para>Ôï ðëÝïí ïñáôü áíôéêåßìåíï åßíáé ï åéêïíéêüò äßóêïò, ï ïðïßïò
êáëåßôáé êáé <emphasis>ôüìïò (volume)</emphasis>. Ïé ôüìïé Ý÷ïõí
ïõóéáóôéêÜ ôéò ßäéåò éäéüôçôåò ìå Ýíá äßóêï ôïõ &unix;, áí êáé
õðÜñ÷ïõí êÜðïéåò ìéêñÝò äéáöïñÝò. Äåí õðÜñ÷ïõí ðåñéïñéóìïß üóï
áöïñÜ ôï ìÝãåèïò ôïõò.</para>
</listitem>
<listitem>
<para>Ïé ôüìïé áðïôåëïýíôáé áðü <emphasis>plex</emphasis>, êáé êÜèå
Ýíá áðü áõôÜ áíôéðñïóùðåýåé ôï óõíïëéêü ÷þñï äéåõèýíóåùí åíüò
ôüìïõ. Áõôü ôï åðßðåäï óôçí éåñáñ÷ßá ðáñÝ÷åé ôç äõíáôüôçôá
redundancy. Ìðïñåßôå íá óêåöôåßôå ôá plex ùò ìåìïíùìÝíïõò äßóêïõò
óå ìéá óõóôïé÷ßá mirror, üðïõ êÜèå Ýíá ðåñéÝ÷åé ôá ßäéá
äåäïìÝíá.</para>
</listitem>
<listitem>
<para>Êáèþò ôï Vinum õðÜñ÷åé ìÝóá óôï ðëáßóéï ëåéôïõñãéþí ôïõ &unix;
ðïõ ÷ñçóéìïðïéåßôáé ãéá ôçí áðïèÞêåõóç óå äßóêïõò, èá ìðïñïýóå
íá ÷ñçóéìïðïéÞóåé ôéò êáôáôìÞóåéò ôïõ &unix; ùò ôï äïìéêü óôïé÷åßï
ãéá ôç äçìéïõñãßá ôùí plex. Óôçí ðñáãìáôéêüôçôá, ç ëïãéêÞ áõôÞ
áðïäåéêíýåôáé éäéáßôåñá ðåñéïñéóôéêÞ: ïé äßóêïé óôï &unix; ìðïñïýí
íá Ý÷ïõí ðåñéïñéóìÝíï áñéèìü êáôáôìÞóåùí. Áíôßèåôá, ôï Vinum
õðïäéáéñåß ìéá ìüíï êáôÜôìçóç ôïõ &unix;
(ôïí <emphasis>ïäçãü</emphasis>) óå óõíå÷üìåíåò ðåñéï÷Ýò ðïõ
êáëïýíôáé <emphasis>õðïäßóêïé (subdisks)</emphasis>. Ïé õðïäßóêïé
÷ñçóéìïðïéïýíôáé ùò ôá äïìéêÜ óôïé÷åßá ãéá ôá plex.</para>
</listitem>
<listitem>
<para>Ïé õðïäßóêïé âñßóêïíôáé óå <emphasis>ïäçãïýò</emphasis> Vinum,
ðïõ ôç äåäïìÝíç óôéãìÞ åßíáé êáôáôìÞóåéò ôïõ &unix;. Ïé ïäçãïß ôïõ
Vinum ìðïñïýí íá ðåñéÝ÷ïõí ïðïéïäÞðïôå áñéèìü áðü õðïäßóêïõò. Ìå
åîáßñåóç ìéá ìéêñÞ ðåñéï÷Þ óôçí áñ÷Þ ôïõ äßóêïõ (ç ïðïßá
÷ñçóéìïðïéåßôáé ãéá ôçí áðïèÞêåõóç äåäïìÝíùí ñýèìéóçò êáé
êáôÜóôáóçò) üëïò ï õðüëïéðïò ïäçãüò åßíáé äéáèÝóéìïò ãéá áðïèÞêåõóç
äåäïìÝíùí.</para>
</listitem>
</itemizedlist>
<para>Ïé ðáñáêÜôù åíüôçôåò ðåñéãñÜöïõí ôïí ôñüðï ìå ôïí ïðïßï áõôÜ ôá
áíôéêåßìåíá ðáñÝ÷ïõí ôçí ëåéôïõñãéêüôçôá ðïõ áðáéôåßôáé áðü ôï
Vinum.</para>
<sect2>
<title>ÌÝãåèïò Ôüìïõ</title>
<para>Ôá plex ìðïñïýí íá ðåñéëáìâÜíïõí ðïëëáðëïýò õðïäßóêïõò, ðïõ
êáôáíÝìïíôáé óå üëïõò ôïõò ïäçãïýò ôïõ Vinum. Óáí áðïôÝëåóìá, ôï
ìÝãåèïò åíüò óõãêåêñéìÝíïõ äßóêïõ äåí ðåñéïñßæåé ôï ìÝãåèïò ïýôå ôïõ
plex, ïýôå ôïõ ôüìïõ.</para>
</sect2>
<sect2>
<title>ÐëåïíÜæïõóá (Redundant) ÁðïèÞêåõóç ÄåäïìÝíùí</title>
<para>Ôï Vinum õëïðïéåß ôï mirroring ðñïóáñôþíôáò ðïëëáðëÜ plex óå
Ýíá ôüìï. ÊÜèå plex åßíáé ìéá áíáðáñÜóôáóç ôùí äåäïìÝíùí åíüò ôüìïõ.
¸íáò ôüìïò ìðïñåß íá ðåñéÝ÷åé ìåôáîý åíüò êáé ïêôþ plex.</para>
<para>Áí êáé Ýíá plex áíôéðñïóùðåýåé ôá ðëÞñç äåäïìÝíá åíüò ôüìïõ,
åßíáé ðéèáíüí êÜðïéá ìÝñç ôçò áíáðáñÜóôáóçò íá ëåßðïõí áðü ôï öõóéêü
ìÝóï, åßôå åðåéäÞ Ý÷åé ó÷åäéáóôåß ìå áõôü ôï ôñüðï (áí äåí Ý÷åé
ïñéóôåß õðïäßóêïò ãéá êÜðïéá ôìÞìáôá ôïõ plex) Þ áðü ðñüâëçìá (ùò
áðïôÝëåóìá ôçò áðïôõ÷ßáò êÜðïéïõ äßóêïõ). ¼óï õðÜñ÷åé ôïõëÜ÷éóôïí
Ýíá plex ðïõ ìðïñåß íá ðáñÝ÷åé ôá äåäïìÝíá ãéá ôçí ðëÞñç ðåñéï÷Þ
äéåõèýíóåùí ôïõ ôüìïõ, ï ôüìïò åßíáé ðëÞñùò ëåéôïõñãéêüò.</para>
</sect2>
<sect2>
<title>ÈÝìáôá Áðüäïóçò</title>
<para>Ôï Vinum õëïðïéåß ôüóï óõíÝíùóç üóï êáé striping óå åðßðåäï
plex:</para>
<itemizedlist>
<listitem>
<para>¸íá <emphasis>plex óõíÝíùóçò (concatenated)</emphasis>
÷ñçóéìïðïéåß ôçí ðåñéï÷Þ äéåõèýíóåùí êÜèå õðïäßóêïõ ìå ôç
óåéñÜ.</para>
</listitem>
<listitem>
<para>¸íá <emphasis>striped plex</emphasis> ãñÜöåé ôá äåäïìÝíá
óå ëùñßäåò (stripes) ðïõ êáôáíÝìïíôáé óå êÜèå õðïäßóêï. ¼ëïé ïé
õðïäßóêïé ðñÝðåé íá Ý÷ïõí ôï ßäéï ìÝãåèïò êáé ðñÝðåé íá õðÜñ÷ïõí
ôïõëÜ÷éóôïí äýï õðïäßóêïé, ãéá íá îå÷ùñßæïõí óå ó÷Ýóç ìå ôï plex
óõíÝíùóçò.</para>
</listitem>
</itemizedlist>
</sect2>
<sect2>
<title>Åßäç ÏñãÜíùóçò Plex</title>
<para>Ç Ýêäïóç ôïõ Vinum ðïõ ðáñÝ÷åôáé ìå ôï &os; &rel.current;
õëïðïéåß äýï åßäç plex:</para>
<itemizedlist>
<listitem>
<para>Ôá plex óõíÝíùóçò ðñïóöÝñïõí ôç ìåãáëýôåñç åõåëéîßá: ìðïñïýí
íá ðåñéÝ÷ïõí ïðïéïäÞðïôå áñéèìü õðïäßóêùí, êáé ïé õðïäßóêïé áõôïß
ìðïñåß íá åßíáé äéáöïñåôéêïý ìåãÝèïõò. Ôï plex ìðïñåß íá
åðåêôáèåß ðñïóèÝôïíôáò ðåñéóóüôåñïõò õðïäßóêïõò. ×ñåéÜæïíôáé
ëéãüôåñï ÷ñüíï <acronym>CPU</acronym> óå ó÷Ýóç ìå ôá stripes, áí
êáé ç äéáöïñÜ óôç ÷ñÞóç ôçò <acronym>CPU</acronym> äåí åßíáé
ìåôñÞóéìç. Áðü ôçí Üëëç ìåñéÜ, åßíáé ðéï åðéññåðÞ óå
ìç-éóïññïðçìÝíç ëåéôïõñãßá, üðïõ Ýíáò äßóêïò åßíáé ðïëý åíåñãüò
êáé ïé õðüëïéðïé áäñáíïýí.</para>
</listitem>
<listitem>
<para>Ôï ìåãáëýôåñï ðëåïíÝêôçìá ôùí stripes
(<acronym>RAID-0</acronym>), åßíáé üôé Ý÷ïõí ðéï éóïññïðçìÝíç
ëåéôïõñãßá: åðéëÝãïíôáò ôï óùóôü ìÝãåèïò ëùñßäáò (ðåñßðïõ
256 kB), ìðïñåßôå íá åîéóïññïðÞóåôå ôï öïñôßï óå êÜèå äßóêï
ôïõ plex. Ôá ìåéïíåêôÞìáôá áõôÞò ôçò ìåèüäïõ åßíáé (åëáöñÜ) ðéï
ðïëýðëïêïò êþäéêáò êáé ðåñéïñéóìïß óôïõò õðïäßóêïõò: ðñÝðåé üëïé
íá åßíáé ôï ßäéï ìÝãåèïò êáé ç åðÝêôáóç åíüò plex ìå ðñïóèÞêç
ðåñéóóüôåñùí äßóêùí åßíáé ôüóï ðïëýðëïêç ðïõ ôç äåäïìÝíç óôéãìÞ
ôï Vinum äåí ôçí õëïðïéåß. Ôï Vinum åðßóçò åðéâÜëëåé Ýíá áêüìá
áðëïúêü ðåñéïñéóìü: Ýíá plex ôýðïõ stripe ðñÝðåé íá äéáèÝôåé
õðï÷ñåùôéêÜ äýï ôïõëÜ÷éóôïí õðïäßóêïõò, äéáöïñåôéêÜ åßíáé
áäýíáôï íá ôï îå÷ùñßóïõìå áðü Ýíá plex óõíÝíùóçò.</para>
</listitem>
</itemizedlist>
<para>Ï <xref linkend="vinum-comparison"/> äåß÷íåé ðåñéëçðôéêÜ ôá
ðëåïíåêôÞìáôá êáé ìåéïíåêôÞìáôá êÜèå åßäïõò ïñãÜíùóçò plex.</para>
<table id="vinum-comparison" frame="none">
<title>Åßäç ÏñãÜíùóçò Vinum Plex</title>
<tgroup cols="5">
<thead>
<row>
<entry>Ôýðïò plex</entry>
<entry>ÅëÜ÷éóôï ðëÞèïò õðïäßóêùí</entry>
<entry>Äõíáôüôçôá ðñïóèÞêçò õðïäßóêùí</entry>
<entry>Ïé õðïäßóêïé ðñÝðåé íá åßíáé ßäéïõ ìåãÝèïõò</entry>
<entry>ÅöáñìïãÞ</entry>
</row>
</thead>
<tbody>
<row>
<entry>óõíÝíùóçò (concatenated)</entry>
<entry>1</entry>
<entry>íáé</entry>
<entry>ü÷é</entry>
<entry>ÁðïèÞêåõóç ìåãÜëïõ üãêïõ äåäïìÝíùí ìå ìÝãéóôç åõåëéîßá
óôïí ôñüðï êáôáíïìÞò êáé ìÝôñéá áðüäïóç.</entry>
</row>
<row>
<entry>striped</entry>
<entry>2</entry>
<entry>ü÷é</entry>
<entry>íáé</entry>
<entry>ÕøçëÞ áðüäïóç óå óõíäõáóìü ìå ðïëý êáëÝò ôá÷ýôçôåò óå
êáôáóôÜóåéò ðïëëáðëÞò ðñüóâáóçò.</entry>
</row>
</tbody>
</tgroup>
</table>
</sect2>
</sect1>
<sect1 id="vinum-examples">
<title>ÌåñéêÜ Ðáñáäåßãìáôá</title>
<para>Ôï Vinum äéáôçñåß ìéá
<emphasis>âÜóç äåäïìÝíùí ìå ôéò ñõèìßóåéò ôïõ</emphasis> ç ïðïßá
ðåñéãñÜöåé ôá áíôéêåßìåíá ôá ïðïßá ãíùñßæåé Ýíá óõãêåêñéìÝíï óýóôçìá.
Áñ÷éêÜ, ï ÷ñÞóôçò äçìéïõñãåß áõôÞ ôç âÜóç äåäïìÝíùí áðü Ýíá Þ
ðåñéóóüôåñá áñ÷åßá ñõèìßóåùí, ìå ôçí âïÞèåéá ôïõ ðñïãñÜììáôïò
&man.gvinum.8;. Ôï vinum áðïèçêåýåé Ýíá áíôßãñáöï ôçò âÜóçò
äåäïìÝíùí óå êÜèå slice ôïõ äßóêïõ (ðïõ ôï Vinum áðïêáëåß
<emphasis>óõóêåõÞ</emphasis>) ðïõ âñßóêåôáé õðü ôïí Ýëåã÷ï ôïõ.
Ç âÜóç äåäïìÝíùí áíáíåþíåôáé óå êÜèå áëëáãÞ êáôÜóôáóçò, þóôå
üëá ôá áíôéêåßìåíá ôïõ Vinum íá åðáíÝñ÷ïíôáé óôç óùóôÞ êáôÜóôáóç ìåôÜ
áðü ìéá åðáíåêêßíçóç.</para>
<sect2>
<title>Ôï Áñ÷åßï Ñõèìßóåùí</title>
<para>Ôï áñ÷åßï ñõèìßóåùí ðåñéãñÜöåé ôá ìåìïíùìÝíá áíôéêåßìåíá ôïõ
Vinum. Ï ïñéóìüò ãéá Ýíá áðëü ôüìï ìðïñåß íá ìïéÜæåé ìå ôïí
ðáñáêÜôù:</para>
<programlisting>
drive a device /dev/da3h
volume myvol
plex org concat
sd length 512m drive a</programlisting>
<para>Áõôü ôï áñ÷åßï ðåñéãñÜöåé ôÝóóåñá áíôéêåßìåíá ôïõ Vinum:</para>
<itemizedlist>
<listitem>
<para>Ç ãñáììÞ <emphasis>drive</emphasis> ðåñéãñÜöåé ìéá êáôÜôìçóç
äßóêïõ (<emphasis>ïäçãïý</emphasis>) êáé ôç èÝóç ôçò óå ó÷Ýóç ìå
ôï öõóéêü äßóêï. Äßíåôáé óå áõôÞ ôï óõìâïëéêü üíïìá
<emphasis>a</emphasis>. Áõôüò ï äéá÷ùñéóìüò ôùí óõìâïëéêþí áðü
ôá ðñáãìáôéêÜ ïíüìáôá óõóêåõþí, ìáò åðéôñÝðåé íá ìåôáöÝñïõìå
äßóêïõò áðü ìéá èÝóç óå ìéá Üëëç ÷ùñßò íá ðñïêëçèåß
óýã÷õóç.</para>
</listitem>
<listitem>
<para>Ç ãñáììÞ <emphasis>volume</emphasis> ðåñéãñÜöåé Ýíá ôüìï.
Ôï ìüíï áðáéôïýìåíï ÷áñáêôçñéóôéêü åäþ åßíáé ôï üíïìá, óôçí
ðåñßðôùóç ìáò <emphasis>myvol</emphasis>.</para>
</listitem>
<listitem>
<para>Ç ãñáììÞ <emphasis>plex</emphasis> ïñßæåé Ýíá plex.
Ç ìüíç áðáñáßôçôç ðáñÜìåôñïò åßíáé ôï åßäïò ôçò ïñãÜíùóçò, óôç
óõãêåêñéìÝíç ðåñßðôùóç ôï <emphasis>concat</emphasis>. Äåí
åßíáé áðáñáßôçôï íá äïèåß üíïìá: ôï óýóôçìá ðáñÜãåé áõôüìáôá
Ýíá üíïìá ÷ñçóéìïðïéþíôáò ôï üíïìá ôïõ ôüìïõ êáé ôçí êáôÜëçîç
<emphasis>.p</emphasis><emphasis>x</emphasis>, üðïõ ôï
<emphasis>x</emphasis> åßíáé ï áñéèìüò ôïõ plex óôïí ôüìï. ¸ôóé,
áõôü ôï plex èá êáëåßôáé <emphasis>myvol.p0</emphasis>.</para>
</listitem>
<listitem>
<para>Ç ãñáììÞ <emphasis>sd</emphasis> ðåñéãñÜöåé Ýíá õðïäßóêï.
Ïé åëÜ÷éóôåò áðáéôïýìåíåò ðñïäéáãñáöÝò åßíáé ôï üíïìá åíüò
äßóêïõ óôïí ïðïßï èá áðïèçêåõôåß, êáé ôï ìÞêïò ôïõ õðïäßóêïõ.
¼ðùò óõìâáßíåé êáé ìå ôá plex, äåí áðáéôåßôáé üíïìá:
ôï óýóôçìá áðïäßäåé ïíüìáôá áõôüìáôá, ÷ñçóéìïðïéþíôáò ùò óçìåßï
åêêßíçóçò ôï üíïìá ôïõ plex êáé ðñïóèÝôïíôáò ôçí êáôÜëçîç
<emphasis>.s</emphasis><emphasis>x</emphasis>, üðïõ ôï
<emphasis>x</emphasis> åßíáé ï áñéèìüò ôïõ õðïäßóêïõ óôï plex.
¸ôóé, ôï Vinum äßíåé óå áõôüí ôïí õðïäßóêï ôï üíïìá
<emphasis>myvol.p0.s0</emphasis>.</para>
</listitem>
</itemizedlist>
<para>ÌåôÜ ôçí åðåîåñãáóßá áõôïý ôïõ áñ÷åßïõ, ôï &man.gvinum.8; ðáñÜãåé
ôçí áêüëïõèç Ýîïäï:</para>
<programlisting width="97">
&prompt.root; gvinum -> <userinput>create config1</userinput>
Configuration summary
Drives: 1 (4 configured)
Volumes: 1 (4 configured)
Plexes: 1 (8 configured)
Subdisks: 1 (16 configured)
D a State: up Device /dev/da3h Avail: 2061/2573 MB (80%)
V myvol State: up Plexes: 1 Size: 512 MB
P myvol.p0 C State: up Subdisks: 1 Size: 512 MB
S myvol.p0.s0 State: up PO: 0 B Size: 512 MB</programlisting>
<para>Ç ðáñáðÜíù Ýîïäïò ÷ñçóéìïðïéåß ôç ìïñöÞ óõíôïìåõìÝíçò ëßóôáò ôïõ
&man.gvinum.8;. Ç ãñáöéêÞ áðåéêüíéóç öáßíåôáé óôï <xref
linkend="vinum-simple-vol"/>.</para>
<para>
<figure id="vinum-simple-vol">
<title>¸íáò Áðëüò Ôüìïò Vinum</title>
<graphic fileref="vinum/vinum-simple-vol"/>
</figure>
</para>
<para>Óôï ó÷Þìá áõôü (êáèþò êáé óå áõôÜ ðïõ áêïëïõèïýí) õðÜñ÷åé ç
áíáðáñÜóôáóç åíüò ôüìïõ ðïõ ðåñéÝ÷åé ôá plex, ôá ïðïßá ìå ôç
óåéñÜ ôïõò ðåñéÝ÷ïõí ôïõò õðïäßóêïõò. Óå áõôü ôï áðëïõóôåõìÝíï
ðáñÜäåéãìá, ï ôüìïò ðåñéÝ÷åé Ýíá plex êáé ôï plex ðåñéÝ÷åé Ýíá
õðïäßóêï.</para>
<para>Ï ôüìïò áõôüò äåí Ý÷åé êÜðïéï óõãêåêñéìÝíï
ðëåïíÝêôçìá óå ó÷Ýóç ìå ìéá óõìâáôéêÞ êáôÜôìçóç äßóêïõ. ÐåñéÝ÷åé
Ýíá ìüíï plex, Üñá äåí Ý÷åé êÜðïéá éêáíüôçôá áíï÷Þò óöáëìÜôùí.
Ôï plex ðåñéÝ÷åé åðßóçò Ýíá õðïäßóêï, êáé Ýôóé äåí õðÜñ÷åé äéáöïñÜ
óôçí êáôáíïìÞ ÷þñïõ óå ó÷Ýóç ìå ìéá óõìâáôéêÞ êáôÜôìçóç. Óôéò
åðüìåíåò åíüôçôåò èá äåßîïõìå äéáöïñåôéêÝò êáé ðéï åíäéáöÝñïõóåò
ìåèüäïõò ñýèìéóçò.</para>
</sect2>
<sect2>
<title>ÁõîçìÝíç Áîéïðéóôßá: Mirroring</title>
<para>Ç áîéïðéóôßá åíüò ôüìïõ ìðïñåß íá áõîçèåß ìÝóù ôïõ mirroring
(êáèñåðôéóìïý). ¼ôáí ó÷åäéÜæåôå Ýíá ôüìï óôïí ïðïßï èá ãßíåé
mirroring, åßíáé óçìáíôéêü íá åîáóöáëßóåôå üôé ïé õðïäßóêïé óå êÜèå
plex åßíáé óå äéáöïñåôéêïýò ïäçãïýò, þóôå ç áðïôõ÷ßá åíüò äßóêïõ íá
ìçí ðñïêáëÝóåé ðáýóç ëåéôïõñãßáò êáé óôá äýï plex. Ôï ðáñáêÜôù
ðáñÜäåéãìá äåß÷íåé ðùò ìðïñåß íá ãßíåé mirroring åíüò ôüìïõ:</para>
<programlisting>
drive b device /dev/da4h
volume mirror
plex org concat
sd length 512m drive a
plex org concat
sd length 512m drive b</programlisting>
<para>Óôï ðáñÜäåéãìá áõôü, äåí Þôáí áðáñáßôçôï íá êáèïñéóôåß îáíÜ ï
ïäçãüò <emphasis>a</emphasis>, êáèþò ôï Vinum äéáèÝôåé Þäç ôéò
áíôßóôïé÷åò êáôá÷ùñßóåéò óôç âÜóç äåäïìÝíùí ìå ôéò ñõèìßóåéò ôïõ.
ÌåôÜ ôçí åðåîåñãáóßá ôùí ðáñáðÜíù ïñéóìþí, ç ñýèìéóç ìïéÜæåé ìå
ôçí ðáñáêÜôù:</para>
<programlisting width="97">
Drives: 2 (4 configured)
Volumes: 2 (4 configured)
Plexes: 3 (8 configured)
Subdisks: 3 (16 configured)
D a State: up Device /dev/da3h Avail: 1549/2573 MB (60%)
D b State: up Device /dev/da4h Avail: 2061/2573 MB (80%)
V myvol State: up Plexes: 1 Size: 512 MB
V mirror State: up Plexes: 2 Size: 512 MB
P myvol.p0 C State: up Subdisks: 1 Size: 512 MB
P mirror.p0 C State: up Subdisks: 1 Size: 512 MB
P mirror.p1 C State: initializing Subdisks: 1 Size: 512 MB
S myvol.p0.s0 State: up PO: 0 B Size: 512 MB
S mirror.p0.s0 State: up PO: 0 B Size: 512 MB
S mirror.p1.s0 State: empty PO: 0 B Size: 512 MB</programlisting>
<para>Ôï <xref linkend="vinum-mirrored-vol"/> áíáðáñéóôÜ áõôÞ ôç äïìÞ
ãñáöéêÜ.</para>
<para>
<figure id="vinum-mirrored-vol">
<title>¸íáò Mirrored Ôüìïò Vinum </title>
<graphic fileref="vinum/vinum-mirrored-vol"/>
</figure>
</para>
<para>Óôï ðáñÜäåéãìá áõôü, êÜèå plex ðåñéÝ÷åé ôçí ðëÞñç ðåñéï÷Þ
äéåõèýíóåùí, ìåãÝèïõò 512 MB. ¼ðùò êáé óôï ðñïçãïýìåíï
ðáñÜäåéãìá, êÜèå plex ðåñéÝ÷åé Ýíá ìïíáäéêü õðïäßóêï.</para>
</sect2>
<sect2>
<title>Âåëôéóôïðïéþíôáò ôçí Áðüäïóç</title>
<para>Ï mirrored ôüìïò ôïõ ðñïçãïýìåíïõ ðáñáäåßãìáôïò ðáñïõóéÜæåé
ìåãáëýôåñç áíï÷Þ óöáëìÜôùí óå ó÷Ýóç ìå Ýíá ôüìï ðïõ äåí ÷ñçóéìïðïéåß
mirror, áëëÜ ç áðüäïóç ôïõ åßíáé ìéêñüôåñç: êÜèå åããñáöÞ óôïí
ôüìï ðñÝðåé íá ãßíåôáé êáé óôïõò äýï äßóêïõò, ÷ñçóéìïðïéþíôáò Ýôóé
ìåãáëýôåñï ðïóïóôü ôïõ äéáèÝóéìïõ åýñïõò æþíçò. Ïé áðáéôÞóåéò ðïõ
åíäå÷ïìÝíùò Ý÷ïõìå ãéá áðüäïóç, áðáéôïýí äéáöïñåôéêÞ ðñïóÝããéóç:
áíôß íá ÷ñçóéìïðïéÞóïõìå mirror, ìðïñïýìå íá äçìéïõñãÞóïõìå ëùñßäåò
áðïèÞêåõóçò (stripes) óå üóï ôï äõíáôüí ðåñéóóüôåñïõò äßóêïõò.
Ç ðáñáêÜôù ñýèìéóç äåß÷íåé Ýíá ôüìï óôïí ïðïßï ôï plex Ý÷åé ãßíåé
stripe óå ôÝóóåñéò äßóêïõò:</para>
<programlisting>
drive c device /dev/da5h
drive d device /dev/da6h
volume stripe
plex org striped 512k
sd length 128m drive a
sd length 128m drive b
sd length 128m drive c
sd length 128m drive d</programlisting>
<para>¼ðùò êáé ðñïçãïõìÝíùò, äåí ÷ñåéÜæåôáé íá ïñßóïõìå îáíÜ ôïõò
äßóêïõò ðïõ åßíáé Þäç ãíùóôïß óôï Vinum. ÌåôÜ ôçí åðåîåñãáóßá ôïõ
ðáñáðÜíù ïñéóìïý, ç ñýèìéóç èá ìïéÜæåé ìå ôçí ðáñáêÜôù:</para>
<programlisting width="92">
Drives: 4 (4 configured)
Volumes: 3 (4 configured)
Plexes: 4 (8 configured)
Subdisks: 7 (16 configured)
D a State: up Device /dev/da3h Avail: 1421/2573 MB (55%)
D b State: up Device /dev/da4h Avail: 1933/2573 MB (75%)
D c State: up Device /dev/da5h Avail: 2445/2573 MB (95%)
D d State: up Device /dev/da6h Avail: 2445/2573 MB (95%)
V myvol State: up Plexes: 1 Size: 512 MB
V mirror State: up Plexes: 2 Size: 512 MB
V striped State: up Plexes: 1 Size: 512 MB
P myvol.p0 C State: up Subdisks: 1 Size: 512 MB
P mirror.p0 C State: up Subdisks: 1 Size: 512 MB
P mirror.p1 C State: initializing Subdisks: 1 Size: 512 MB
P striped.p1 State: up Subdisks: 1 Size: 512 MB
S myvol.p0.s0 State: up PO: 0 B Size: 512 MB
S mirror.p0.s0 State: up PO: 0 B Size: 512 MB
S mirror.p1.s0 State: empty PO: 0 B Size: 512 MB
S striped.p0.s0 State: up PO: 0 B Size: 128 MB
S striped.p0.s1 State: up PO: 512 kB Size: 128 MB
S striped.p0.s2 State: up PO: 1024 kB Size: 128 MB
S striped.p0.s3 State: up PO: 1536 kB Size: 128 MB</programlisting>
<para>
<figure id="vinum-striped-vol">
<title>¸íáò Striped Ôüìïò Vinum</title>
<graphic fileref="vinum/vinum-striped-vol"/>
</figure>
</para>
<para>Áõôüò ï ôüìïò áíáðáñßóôáôáé ãñáöéêÜ óôï
<xref linkend="vinum-striped-vol"/>. Ç áðü÷ñùóç ôçò ëùñßäáò
áíôéðñïóùðåýåé ôç èÝóç ôçò ìÝóá óôçí ðåñéï÷Þ äéåõèýíóåùí ôïõ plex:
ïé áíïé÷ôü÷ñùìåò ëùñßäåò åßíáé ïé ðñþôåò, ïé óêïõñü÷ñùìåò åßíáé ïé
ôåëåõôáßåò.</para>
</sect2>
<sect2>
<title>Áîéïðéóôßá êáé Áðüäïóç</title>
<para><anchor id="vinum-resilience"/>Ìå ôï êáôÜëëçëï õëéêü, åßíáé äõíáôüí
íá äçìéïõñãçèïýí ôüìïé ïé ïðïßïé íá ðáñïõóéÜæïõí ôüóï ìåãÜëç áíï÷Þ
óå óöÜëìáôá, üóï êáé áõîçìÝíç áðüäïóç óå ó÷Ýóç ìå ôéò ôõðïðïéçìÝíåò
êáôáôìÞóåéò ôïõ &unix;. ¸íá ôõðéêü áñ÷åßï ñõèìßóåùí èá ìïéÜæåé ìå ôï
ðáñáêÜôù:</para>
<programlisting>
volume raid10
plex org striped 512k
sd length 102480k drive a
sd length 102480k drive b
sd length 102480k drive c
sd length 102480k drive d
sd length 102480k drive e
plex org striped 512k
sd length 102480k drive c
sd length 102480k drive d
sd length 102480k drive e
sd length 102480k drive a
sd length 102480k drive b</programlisting>
<para>Ïé õðïäßóêïé ôïõ äåýôåñïõ plex Ý÷ïõí ìåôáôåèåß êáôÜ äýï ïäçãïýò
óå ó÷Ýóç ìå áõôïýò ôïõ ðñþôïõ plex: áõôü åîáóöáëßæåé üôé ïé åããñáöÝò
äåí ãßíïíôáé óôïõò ßäéïõò õðïäßóêïõò, áêüìá êáé áí ìéá ìåôáöïñÜ
÷ñçóéìïðïéåß êáé ôïõò äýï äßóêïõò.</para>
<para>Ôï <xref linkend="vinum-raid10-vol"/> áíáðáñéóôÜ ãñáöéêÜ ôç äïìÞ
áõôïý ôïõ ôüìïõ.</para>
<para>
<figure id="vinum-raid10-vol">
<title>¸íáò Mirrored êáé Striped Ôüìïò ôïõ Vinum</title>
<graphic fileref="vinum/vinum-raid10-vol"/>
</figure>
</para>
</sect2>
</sect1>
<sect1 id="vinum-object-naming">
<title>Ïíïìáóßá ÁíôéêåéìÝíùí</title>
<para>¼ðùò ðåñéãñÜøáìå ðáñáðÜíù, ôï Vinum áðïäßäåé ðñïåðéëåãìÝíá ïíüìáôá
óå plex êáé õðïäßóêïõò, áí êáé õðÜñ÷åé ç äõíáôüôçôá íá ôá
ðáñáêÜìøåôå. Áõôü ùóôüóï äåí óõíßóôáôáé: ç åìðåéñßá ðïõ Ý÷ïõìå áðü
ôï äéá÷åéñéóôÞ ôüìùí VERITAS (ï ïðïßïò åðéôñÝðåé åëåýèåñç áðüäïóç
ïíïìÜôùí óôá áíôéêåßìåíá) Ý÷åé äåßîåé üôé áõôïý ôïõ åßäïõò ç åõåëéîßá
äåí ðñïóöÝñåé óçìáíôéêÜ ðëåïíåêôÞìáôá, êáé ìðïñåß íá ðñïêáëÝóåé
óýã÷õóç.</para>
<para>Ôá ïíüìáôá ìðïñåß íá ðåñéÝ÷ïõí ïðïéïäÞðïôå ìç-êåíü ÷áñáêôÞñá, áëëÜ
óõíßóôáôáé íá ðåñéïñéóôåßôå óôç ÷ñÞóç ãñáììÜôùí, áñéèìþí êáé ôçò êÜôù
ðáýëáò. Ôá ïíüìáôá ôùí ôüìùí, ôùí plex êáé ôùí õðïäßóêùí ìðïñåß íá
åßíáé ìÝ÷ñé 64 ÷áñáêôÞñåò, åíþ ôá ïíüìáôá ôùí äßóêùí ìðïñåß íá åßíáé
ìÝ÷ñé 32 ÷áñáêôÞñåò.</para>
<para>Ôá áñ÷åßá óõóêåõþí ôïõ Vinum äçìéïõñãïýíôáé óôïí êáôÜëïãï
<filename class="directory">/dev/gvinum</filename>. Ìå ôéò ñõèìßóåéò
ðïõ öáßíïíôáé ðáñáðÜíù, ôï Vinum èá äçìéïõñãÞóåé ôá ðáñáêÜôù áñ÷åßá
óõóêåõþí:</para>
<itemizedlist>
<listitem>
<para>Êáôá÷ùñßóåéò óõóêåõþí ãéá êÜèå ôüìï. ÁõôÝò åßíáé êáé ïé êýñéåò
óõóêåõÝò ðïõ ÷ñçóéìïðïéåß ôï Vinum. Ìå ôéò ñõèìßóåéò ðïõ äåßîáìå
ðáñáðÜíù, èá Ý÷ïõìå ôéò óõóêåõÝò:
<filename class="devicefile">/dev/gvinum/myvol</filename>,
<filename class="devicefile">/dev/gvinum/mirror</filename>,
<filename class="devicefile">/dev/gvinum/striped</filename>,
<filename class="devicefile">/dev/gvinum/raid5</filename> êáé
<filename class="devicefile">/dev/gvinum/raid10</filename>.</para>
</listitem>
<listitem>
<para>¼ëïé ïé ôüìïé äéáèÝôïõí áðåõèåßáò êáôá÷ùñßóåéò óôïí êáôÜëïãï
<filename class="directory">/dev/gvinum/</filename>.</para>
</listitem>
<listitem>
<para>Ïé êáôÜëïãïé
<filename class="directory">/dev/gvinum/plex</filename> êáé
<filename class="directory">/dev/gvinum/sd</filename>, ðïõ
ðåñéÝ÷ïõí ôá áñ÷åßá óõóêåõþí ãéá êÜèå plex êáé õðïäßóêï
áíôßóôïé÷á.</para>
</listitem>
</itemizedlist>
<para>Ãéá ðáñÜäåéãìá, èåùñÞóôå ôï ðáñáêÜôù áñ÷åßï ñõèìßóåùí:</para>
<programlisting>
drive drive1 device /dev/sd1h
drive drive2 device /dev/sd2h
drive drive3 device /dev/sd3h
drive drive4 device /dev/sd4h
volume s64 setupstate
plex org striped 64k
sd length 100m drive drive1
sd length 100m drive drive2
sd length 100m drive drive3
sd length 100m drive drive4</programlisting>
<para>ÌåôÜ ôçí åðåîåñãáóßá áõôïý ôïõ áñ÷åßïõ, ôï &man.gvinum.8; èá
äçìéïõñãÞóåé ôçí áêüëïõèç äïìÞ óôïí êáôÜëïãï
<filename class="directory">/dev/gvinum</filename>:</para>
<programlisting>
drwxr-xr-x 2 root wheel 512 Apr 13 16:46 plex
crwxr-xr-- 1 root wheel 91, 2 Apr 13 16:46 s64
drwxr-xr-x 2 root wheel 512 Apr 13 16:46 sd
/dev/vinum/plex:
total 0
crwxr-xr-- 1 root wheel 25, 0x10000002 Apr 13 16:46 s64.p0
/dev/vinum/sd:
total 0
crwxr-xr-- 1 root wheel 91, 0x20000002 Apr 13 16:46 s64.p0.s0
crwxr-xr-- 1 root wheel 91, 0x20100002 Apr 13 16:46 s64.p0.s1
crwxr-xr-- 1 root wheel 91, 0x20200002 Apr 13 16:46 s64.p0.s2
crwxr-xr-- 1 root wheel 91, 0x20300002 Apr 13 16:46 s64.p0.s3</programlisting>
<para>Áí êáé óõíßóôáôáé íá ìçí äßíïíôáé óõãêåêñéìÝíá ïíüìáôá óôá plex
êáé ôïõò õðïäßóêïõò, èá ðñÝðåé íá äïèïýí ïíüìáôá óôïõò äßóêïõò ôïõ
Vinum. Ìå ôïí ôñüðï áõôü, ï äßóêïò áíáãíùñßæåôáé áõôüìáôá áêüìá êáé
áí áëëÜîåé èÝóç. Ôá ïíüìáôá ôùí äßóêùí ìðïñåß íá Ý÷ïõí ìÝãåèïò ìÝ÷ñé
32 ÷áñáêôÞñåò.</para>
<sect2>
<title>Äçìéïõñãßá ÓõóôçìÜôùí Áñ÷åßùí</title>
<para>Ïé ôüìïé äåß÷íïõí üìïéïé ìå ôïõò äßóêïõò üóï áöïñÜ ôï óýóôçìá,
ìå ìéá åîáßñåóç. Áíôßèåôá ìå ôïõò äßóêïõò ôïõ &unix;, ôï Vinum äåí
äçìéïõñãåß êáôáôìÞóåéò óôïõò ôüìïõò, êáé Ýôóé áðïõóéÜæåé áðü áõôïýò
ï áíôßóôïé÷ïò ðßíáêáò êáôáôìÞóåùí. Áõôü áðáéôåß ôçí ôñïðïðïßçóç
êÜðïéùí âïçèçôéêþí ðñïãñáììÜôùí êáé åéäéêüôåñá ôïõ &man.newfs.8;, ôï
ïðïßï óôéò ðñïçãïýìåíåò õëïðïéÞóåéò ôïõ ðñïóðáèïýóå íá åñìçíåýóåé
ôï ôåëåõôáßï ãñÜììá åíüò ôüìïõ Vinum ùò áíáãíùñéóôéêü ôçò êáôÜôìçóçò.
Ãéá ðáñÜäåéãìá, Ýíáò êáíïíéêüò äßóêïò ìðïñåß íá Ý÷åé ôï üíïìá
<filename class="devicefile">/dev/ad0a</filename> Þ
<filename class="devicefile">/dev/da2h</filename>.
Ôá ïíüìáôá áõôÜ áíôéðñïóùðåýïõí ôçí ðñþôç êáôÜôìçóç
(<devicename>a</devicename>) óôïí ðñþôï äßóêï IDE
(<devicename>ad</devicename>) êáé ôçí üãäïç êáôÜôìçóç
(<devicename>h</devicename>) óôïí ôñßôï (2) SCSI äßóêï
(<devicename>da</devicename>) áíôßóôïé÷á. Óå áíôßèåóç, Ýíáò ôüìïò
ôïõ Vinum ìðïñåß íá ïíïìÜæåôáé <filename
class="devicefile">/dev/gvinum/concat</filename>, ôï ïðïßï äåí
Ý÷åé êáìéÜ ó÷Ýóç ìå üíïìá êáôÜôìçóçò.</para>
<para>Ãéá íá äçìéïõñãÞóåôå Ýíá óýóôçìá áñ÷åßùí óå áõôü ôïí ôüìï,
÷ñçóéìïðïéÞóôå ôçí &man.newfs.8;:</para>
<screen>&prompt.root; <userinput>newfs /dev/gvinum/concat</userinput></screen>
</sect2>
</sect1>
<sect1 id="vinum-config">
<title>Ñýèìéóç ôïõ Vinum</title>
<para>Ôï Vinum äåí õðÜñ÷åé óôïí ðõñÞíá <filename>GENERIC</filename>.
Åßíáé äõíáôüí íá äçìéïõñãÞóåôå ðñïóáñìïóìÝíï ðõñÞíá ðïõ íá ôï ðåñéÝ÷åé,
áëëÜ äåí óõíßóôáôáé. Ï óõíçèéóìÝíïò ôñüðïò íá îåêéíÞóåôå ôï Vinum,
åßíáé íá ôï öïñôþóåôå ùò Üñèñùìá óôïí ðõñÞíá (<acronym>kld</acronym>).
Äåí ÷ñåéÜæåôáé êáí íá ÷ñçóéìïðïéÞóåôå ôçí &man.kldload.8; ãéá ôï
Vinum: üôáí îåêéíÞóåôå ôï &man.gvinum.8;, èá ãßíåé Ýëåã÷ïò ãéá íá
äéáðéóôùèåß áí ôï Üñèñùìá åßíáé öïñôùìÝíï, êáé áí äåí åßíáé èá
öïñôùèåß áõôüìáôá.</para>
<sect2>
<title>Åêêßíçóç</title>
<para>Ôï Vinum áðïèçêåýåé ôéò ðëçñïöïñßåò ãéá ôéò ñõèìßóåéò ôïõ óôá
slices ôùí äßóêùí, ïõóéáóôéêÜ ìå ôïí ßäéï ôñüðï ðïõ ôéò áðïèçêåýåé
êáé óôá áñ÷åßá ñõèìßóåùí. ¼ôáí ôï Vinum äéáâÜæåé ôç âÜóç äåäïìÝíùí
ôùí ñõèìßóåùí, ìðïñåß íá áíáãíùñßóåé Ýíá áñéèìü ëÝîåùí ðïõ äåí
åðéôñÝðåôáé íá åìöáíéóôïýí óôá áñ÷åßá ñõèìßóåùí. Ãéá ðáñÜäåéãìá, ïé
ñõèìßóåéò ãéá êÜðïéï äßóêï ìðïñåß íá ðåñéÝ÷ïõí ôï ðáñáêÜôù
êåßìåíï:</para>
<programlisting width="119">volume myvol state up
volume bigraid state down
plex name myvol.p0 state up org concat vol myvol
plex name myvol.p1 state up org concat vol myvol
plex name myvol.p2 state init org striped 512b vol myvol
plex name bigraid.p0 state initializing org raid5 512b vol bigraid
sd name myvol.p0.s0 drive a plex myvol.p0 state up len 1048576b driveoffset 265b plexoffset 0b
sd name myvol.p0.s1 drive b plex myvol.p0 state up len 1048576b driveoffset 265b plexoffset 1048576b
sd name myvol.p1.s0 drive c plex myvol.p1 state up len 1048576b driveoffset 265b plexoffset 0b
sd name myvol.p1.s1 drive d plex myvol.p1 state up len 1048576b driveoffset 265b plexoffset 1048576b
sd name myvol.p2.s0 drive a plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 0b
sd name myvol.p2.s1 drive b plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 524288b
sd name myvol.p2.s2 drive c plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 1048576b
sd name myvol.p2.s3 drive d plex myvol.p2 state init len 524288b driveoffset 1048841b plexoffset 1572864b
sd name bigraid.p0.s0 drive a plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 0b
sd name bigraid.p0.s1 drive b plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 4194304b
sd name bigraid.p0.s2 drive c plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 8388608b
sd name bigraid.p0.s3 drive d plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 12582912b
sd name bigraid.p0.s4 drive e plex bigraid.p0 state initializing len 4194304b driveoff set 1573129b plexoffset 16777216b</programlisting>
<para>Ïé ðñïöáíåßò äéáöïñÝò åäþ, åßíáé ç ðáñïõóßá óõãêåêñéìÝíùí
èÝóåùí êáé ïíïìÜôùí (êáé ôá äýï åßíáé åðéôñåðôÜ, áëëÜ ãåíéêÜ äåí
óõíßóôáôáé ç ÷ñÞóç ôïõò) êáé ïé ðëçñïöïñßåò êáôÜóôáóçò (ðïõ
äåí åßíáé äéáèÝóéìåò óôï ÷ñÞóôç). Ôï Vinum äåí áðïèçêåýåé
ðëçñïöïñßåò ó÷åôéêÝò ìå ôïõò äßóêïõò óôéò ñõèìßóåéò ôïõ: áðëþò
áíé÷íåýåé üëïõò ôïõò äßóêïõò ãéá êáôáôìÞóåéò ðïõ ðåñéÝ÷ïõí
åôéêÝôá Vinum. Áõôü åðéôñÝðåé óôï Vinum íá áíáãíùñßóåé ôïõò äßóêïõò
óùóôÜ, áêüìá êáé áí ôïõò Ý÷åé äïèåß äéáöïñåôéêü &unix;
áíáãíùñéóôéêü (ID).</para>
<sect3 id="vinum-rc-startup">
<title>Áõôüìáôç Åêêßíçóç</title>
<para>Ôï <emphasis>Gvinum</emphasis> îåêéíÜåé ðÜíôïôå áõôüìáôá
ìåôÜ ôçí öüñôùóç ôïõ áñèñþìáôïò ìÝóù ôïõ &man.loader.conf.5;.
Ãéá íá öïñôþóåôå ôï Üñèñùìá ôïõ <emphasis>Gvinum</emphasis> êáôÜ
ôçí åêêßíçóç, ðñïóèÝóôå ôç ãñáììÞ
<literal>geom_vinum_load="YES"</literal> óôï áñ÷åßï
<filename>/boot/loader.conf</filename>.</para>
<para>¼ôáí îåêéíÜôå ôï Vinum ìå ôçí åíôïëÞ
<command>gvinum start</command>, ôï Vinum äéáâÜæåé ôç âÜóç
äåäïìÝíùí ñõèìßóåùí áðü Ýíáí äßóêï ðïõ âñßóêåôáé õðü ôïí Ýëåã÷ï
ôïõ. ÊÜôù áðü öõóéïëïãéêÝò óõíèÞêåò, êÜèå äßóêïò ðåñéÝ÷åé Ýíá
üìïéï áíôßãñáöï ôçò âÜóçò, Ýôóé äåí Ý÷åé óçìáóßá áðü ðïéï äßóêï èá
ãßíåé ç áíÜãíùóç. Ùóôüóï, ìåôÜ áðü êÜðïéï áðüôïìï ôåñìáôéóìü
ëåéôïõñãßáò, ôï Vinum èá ðñÝðåé íá êáèïñßóåé ðïéïò äßóêïò Ý÷åé ôï
ðéï ðñüóöáôï áíôßãñáöï êáé íá äéáâÜóåé áðü åêåß ôéò ñõèìßóåéò.
ÌåôÜ èá äéïñèþóåé (áí ÷ñåéÜæåôáé) ôéò ñõèìßóåéò êáé óôïõò
õðüëïéðïõò äßóêïõò.</para>
</sect3>
</sect2>
</sect1>
<sect1 id="vinum-root">
<title>×ñÞóç ôïõ Vinum óôï Ñéæéêü Óýóôçìá Áñ÷åßùí</title>
<para>Óå Ýíá ìç÷Üíçìá óôï ïðïßï Ý÷åé ãßíåé ðëÞñåò mirror óôá óõóôÞìáôá
áñ÷åßùí ìå ôç ÷ñÞóç ôïõ Vinum, åßíáé óõíÞèùò åðéèõìçôü íá ãßíåé mirror
êáé óôï ñéæéêü (root) óýóôçìá áñ÷åßùí. Ç ñýèìéóç áõôÞ äåí åßíáé
ôüóï áðëÞ üóï óå Ýíá ïðïéïäÞðïôå óýóôçìá áñ÷åßùí, åðåéäÞ:</para>
<itemizedlist>
<listitem>
<para>Ôï ñéæéêü óýóôçìá áñ÷åßùí ðñÝðåé íá åßíáé äéáèÝóéìï áðü ðïëý
íùñßò êáôÜ ôç äéáäéêáóßá åêêßíçóçò, Ýôóé åßíáé áðáñáßôçôï ïé
õðïäïìÝò ôïõ Vinum íá åßíáé åðßóçò äéáèÝóéìåò ôçí ßäéá
óôéãìÞ.</para>
</listitem>
<listitem>
<para>Ï ôüìïò ðïõ ðåñéÝ÷åé ôï ñéæéêü óýóôçìá áñ÷åßùí ðåñéÝ÷åé åðßóçò
êáé ôïí êþäéêá åêêßíçóçò (bootstrap) êáé ôïí ðõñÞíá, ï ïðïßïò
èá ðñÝðåé íá åßíáé ðñïóâÜóéìïò áðü âáóéêÜ ðñïãñÜììáôá
ôïõ óõóôÞìáôïò (ð.÷. ôï BIOS óå ìç÷áíÞìáôá ôýðïõ PC), ôá ïðïßá äåí
ãíùñßæïõí êáé äåí ìðïñïýí íá ìÜèïõí ôéò ëåðôïìÝñåéåò õëïðïßçóçò ôïõ
Vinum.</para>
</listitem>
</itemizedlist>
<para>Óôéò åðüìåíåò åíüôçôåò, ï üñïò <quote>ñéæéêüò ôüìïò</quote>
÷ñçóéìïðïéåßôáé ãåíéêÜ ãéá íá ðåñéãñÜøåé ôïí ôüìï ôïõ Vinum ðïõ
ðåñéÝ÷åé ôï ñéæéêü óýóôçìá áñ÷åßùí. Åßíáé ãåíéêÜ êáëÞ éäÝá íá
÷ñçóéìïðïéåßôáé ôï üíïìá <literal>"root"</literal> ãéá áõôü ôïí ôüìï,
áëëÜ áõôü äåí áðïôåëåß ôå÷íéêÞ áðáßôçóç. ¼ëá ôá ðáñáäåßãìáôá åíôïëþí
óôéò ðáñáêÜôù åíüôçôåò ÷ñçóéìïðïéïýí ôçí ðáñáðÜíù ðáñáäï÷Þ.</para>
<sect2>
<title>Åêêßíçóç ôïõ Vinum ÁñêåôÜ Íùñßò ãéá ôï Ñéæéêü Óýóôçìá
Áñ÷åßùí</title>
<para>Áõôü ìðïñåß íá åðéôåõ÷èåß ìå äéÜöïñïõò ôñüðïõò:</para>
<itemizedlist>
<listitem>
<para>Ôï Vinum ðñÝðåé íá åßíáé äéáèÝóéìï óôï ðõñÞíá êáôÜ ôçí
åêêßíçóç. Ãéá ôï ëüãï áõôü, ç ìÝèïäïò áõôüìáôçò åêêßíçóçò ðïõ
ðåñéãñÜøáìå óôï <xref linkend="vinum-rc-startup"/> äåí ìðïñåß íá
÷ñçóéìïðïéçèåß óå áõôÞ ôçí ðåñßðôùóç êáé ç ðáñÜìåôñïò
<literal>start_vinum</literal> <emphasis>äåí</emphasis> èá ðñÝðåé
íá ôåèåß üôáí ÷ñçóéìïðïéåßôáé ç ðáñáêÜôù äéÜôáîç. Ìéá ðéèáíÞ
åðéëïãÞ åßíáé íá ìåôáãëùôôßóåôå óôáôéêÜ ôï Vinum óôïí ðõñÞíá
þóôå íá åßíáé äéáèÝóéìï ðÜíôá, áëëÜ áõôü óõíÞèùò äåí åßíáé
åðéèõìçôü. ÕðÜñ÷åé ìéá áêüìá äéáèÝóéìç åðéëïãÞ, íá ïñßóåôå íá
öïñôþíåôáé ôï Üñèñùìá ôïõ ðõñÞíá ìÝóù ôïõ
<filename>/boot/loader</filename> (<xref
linkend="boot-loader"/>) ðñéí ôçí åêêßíçóç ôïõ ßäéïõ ôïõ
ðõñÞíá. Áõôü ìðïñåß íá åðéôåõ÷èåß ìå ôç ãñáììÞ:</para>
<programlisting>geom_vinum_load="YES"</programlisting>
<para>óôï áñ÷åßï <filename>/boot/loader.conf</filename>.</para>
</listitem>
<listitem>
<para>Óôï <emphasis>Gvinum</emphasis>, üëç ç äéáäéêáóßá åêêßíçóçò
ãßíåôáé áõôüìáôá ìåôÜ ôçí öüñôùóç ôïõ áñèñþìáôïò ðõñÞíá, Ýôóé
ç äéáäéêáóßá ðïõ ðåñéãñÜøáìå ðáñáðÜíù åßíáé êáé ç ìüíç ðïõ
áðáéôåßôáé.</para>
</listitem>
</itemizedlist>
</sect2>
<sect2>
<title>Äçìéïõñãßá Ñéæéêïý Ôüìïõ Vinum ìå Äõíáôüôçôá Ðñüóâáóçò áðü ôïí
Êþäéêá Åêêßíçóçò (Bootstrap).</title>
<para>Êáèþò ï ôñÝ÷ïíôáò êþäéêáò åêêßíçóçò ôïõ &os; Ý÷åé ìÝãåèïò ìüíï
7.5 KB, êáé åßíáé Þäç åðéöïñôéóìÝíïò ìå ôçí áíÜãíùóç áñ÷åßùí (üðùò ôï
<filename>/boot/loader</filename>) áðü ôï óýóôçìá áñ÷åßùí UFS, åßíáé
ðñáêôéêÜ áäýíáôï íá ãíùñßæåé êáé ôéò áðáéôïýìåíåò åóùôåñéêÝò äïìÝò
ôïõ Vinum þóôå íá ìðïñåß íá åñìçíåýóåé ôéò áíôßóôïé÷åò ðëçñïöïñßåò
ñýèìéóçò êáé íá ìÜèåé ôéò ëåðôïìÝñåéåò ôïõ ôüìïõ åêêßíçóçò. Ãéá ôï
ëüãï áõôü, ÷ñåéÜæåôáé íá ÷ñçóéìïðïéÞóïõìå êÜðïéá ôå÷íÜóìáôá þóôå íá
äþóïõìå óôïí êþäéêá åêêßíçóçò ôçí øåõäáßóèçóç ýðáñîçò ìéáò êáíïíéêÞò
êáôÜôìçóçò <literal>"a"</literal> ðïõ íá ðåñéÝ÷åé ôï ñéæéêü óýóôçìá
áñ÷åßùí.</para>
<para>Ãéá íá êáôáóôåß áõôü äõíáôü, èá ðñÝðåé íá ðëçñïýíôáé ôáõôü÷ñïíá
üëåò ïé ðáñáêÜôù ðñïûðïèÝóåéò üóï áöïñÜ ôïí ôüìï åêêßíçóçò:</para>
<itemizedlist>
<listitem>
<para>Ï ôüìïò åêêßíçóçò äåí èá ðñÝðåé íá åßíáé stripe Þ
RAID-5.</para>
</listitem>
<listitem>
<para>Ï ôüìïò åêêßíçóçò äåí èá ðñÝðåé íá ðåñéÝ÷åé ðåñéóóüôåñïõò
áðü Ýíá óõíåíùìÝíïõò õðïäßóêïõò áíÜ plex.</para>
</listitem>
</itemizedlist>
<para>Óçìåéþóôå üôé åßíáé óõíÞèùò åðéèõìçôü êáé äõíáôü íá õðÜñ÷ïõí
ðïëëáðëÜ plex, êáèÝíá áðü ôá ïðïßá íá åßíáé áíôßãñáöï ôïõ ñéæéêïý
óõóôÞìáôïò áñ÷åßùí. Ç äéáäéêáóßá åêêßíçóçò èá ÷ñçóéìïðïéÞóåé ùóôüóï
ìüíï Ýíá áðü áõôÜ ôá áíôßãñáöá ãéá íá âñåé ôïí êþäéêá åêêßíçóçò êáé
üëá ôá áñ÷åßá, ìÝ÷ñé íá ãßíåé ôåëéêÜ ç ðñïóÜñôçóç ôïõ ñéæéêïý
óõóôÞìáôïò áñ÷åßùí áðü ôïí ßäéï ôïí ðõñÞíá. ÊÜèå ìïíáäéêüò õðïäßóêïò
ìÝóá óå áõôÜ ôá plex, èá ÷ñåéáóôåß íá äéáèÝôåé ôç äéêÞ ôïõ
øåõôï-êáôÜôìçóç <literal>"a"</literal> þóôå ç óõóêåõÞ íá åßíáé
åêêéíÞóéìç. Äåí åßíáé áðáñáßôçôï êÜèå ìéá áðü áõôÝò ôéò
øåõôï-êáôáôìÞóåéò íá âñßóêåôáé óôçí ßäéá èÝóç ìÝóá óôçí óõóêåõÞ,
óå ó÷Ýóç ìå Üëëåò óõóêåõÝò ðïõ ðåñéÝ÷ïõí plex ìå ñéæéêü óýóôçìá
áñ÷åßùí. Åßíáé üìùò ãåíéêÜ êáëÞ éäÝá íá äçìéïõñãÞóåôå ôïõò ôüìïõò
ôïõ Vinum ìå ôÝôïéï ôñüðï, þóôå ïé óõóêåõÝò mirror ðïõ ðñïêýðôïõí íá
åßíáé óõììåôñéêÝò ãéá íá áðïöýãåôå ôç óýã÷õóç.</para>
<para>Ãéá íá äçìéïõñãçèïýí áõôÝò ïé ôýðïõ <literal>"a"</literal>
êáôáôìÞóåéò ãéá êÜèå óõóêåõÞ ðïõ èá ðåñéÝ÷åé ôìÞìáôá ôïõ ñéæéêïý
ôüìïõ, èá ðñÝðåé íá ãßíïõí ôá áêüëïõèá:</para>
<procedure>
<step>
<para>Èá ðñÝðåé íá åîåôÜóåôå ôç èÝóç (ôçí áðüóôáóç áðü ôçí áñ÷Þ ôçò
óõóêåõÞò) êáé ôï ìÝãåèïò ôçò óõóêåõÞò õðïäßóêïõ ç ïðïßá èá åßíáé
ìÝñïò ôïõ ñéæéêïý ôüìïõ, ÷ñçóéìïðïéþíôáò ôçí åíôïëÞ:</para>
<screen>&prompt.root; <userinput>gvinum l -rv root</userinput></screen>
<para>Óçìåéþóôå üôé óôï Vinum ïé èÝóåéò êáé ôá ìåãÝèç ìåôñïýíôáé
óå bytes. Èá ðñÝðåé íá äéáéñÝóåôå áõôïýò ôïõò áñéèìïýò ìå ôï 512
ãéá íá âñåßôå ôïõò áñéèìïýò ìðëïê ðïõ èá ÷ñçóéìïðïéÞóåôå óôçí
åíôïëÞ <command>bsdlabel</command>.</para>
</step>
<step>
<para>ÅêôåëÝóôå ôçí åíôïëÞ:</para>
<screen>&prompt.root; <userinput>bsdlabel -e <replaceable>devname</replaceable></userinput></screen>
<para>ãéá êÜèå óõóêåõÞ ðïõ óõììåôÝ÷åé óôï ñéæéêü ôüìï.
Ôï <replaceable>devname</replaceable> èá ðñÝðåé íá åßíáé åßôå ôï
üíïìá ôïõ äßóêïõ (ãéá ðáñÜäåéãìá <devicename>da0</devicename>)
ãéá äßóêïõò ÷ùñßò slices (÷ùñßò äçë. êáôáôìÞóåéò fdisk), Þ ôï
üíïìá ôïõ slice (ãéá ðáñÜäåéãìá,
<devicename>ad0s1</devicename>).</para>
<para>Áí õðÜñ÷åé Þäç ìéá êáôÜôìçóç <literal>"a"</literal> óôç
óõóêåõÞ (ðïõ ðéèáíþò ðåñéÝ÷åé ôï ñéæéêü óýóôçìá áñ÷åßùí ðïõ Þôáí
óå ÷ñÞóç ðñéí ÷ñçóéìïðïéçèåß ôï Vinum), èá ðñÝðåé íá ìåôïíïìáóôåß
óå êÜôé Üëëï þóôå íá åîáêïëïõèåß íá åßíáé ðñïóâÜóéìï
(óå ðåñßðôùóç áíÜãêçò), áëëÜ äåí èá ÷ñçóéìïðïéåßôáé ðëÝïí áðü
ðñïåðéëïãÞ ãéá ôçí åêêßíçóç ôïõ óõóôÞìáôïò. Óçìåéþóôå üôé ïé
åíåñãÝò êáôáôìÞóåéò (üðùò ãéá ðáñÜäåéãìá Ýíá ñéæéêü óýóôçìá
áñ÷åßùí ôï ïðïßï åßíáé Þäç ðñïóáñôçìÝíï) äåí ìðïñïýí íá
ìåôïíïìáóôïýí. Èá ðñÝðåé íá åêôåëÝóåôå ôçí åíôïëÞ
÷ñçóéìïðïéþíôáò ôçí åðéëïãÞ <quote>Fixit</quote> ôïõ CD
åãêáôÜóôáóçò, Þ íá áêïëïõèÞóåôå ìéá äéáäéêáóßá äýï âçìÜôùí
(óå ðåñßðôùóç ðïõ Ý÷åôå mirror) îåêéíþíôáò áðü ôïí Ýíá äßóêï êáé
ìåôïíïìÜæïíôáò ôïí Üëëï.</para>
<para>¸ðåéôá èá ðñÝðåé íá ðñïóèÝóåôå ôçí áðüóôáóç (offset, áí
õðÜñ÷åé) ôçò êáôÜôìçóçò Vinum áõôÞò ôçò óõóêåõÞò, ìå ôçí áðüóôáóç
ôïõ õðïäßóêïõ ôïõ áíôßóôïé÷ïõ ñéæéêïý ôüìïõ ôçò óõóêåõÞò. Ç ôéìÞ
ðïõ èá ðñïêýøåé èá åßíáé ç áðüóôáóç (<literal>"offset"</literal>)
ãéá ôç íÝá êáôÜôìçóç <literal>"a"</literal>. Ìðïñåßôå íá ðÜñåôå
áõôïýóéá ôçí ôéìÞ <literal>"size"</literal> ãéá áõôÞ ôçí êáôÜôìçóç
áðü ôïí õðïëïãéóìü ðïõ êÜíáôå ðáñáðÜíù. Ôï
<literal>"fstype"</literal> èá ðñÝðåé íá åßíáé
<literal>4.2BSD</literal>. Ïé ôéìÝò ôùí
<literal>"fsize"</literal>, <literal>"bsize"</literal>,
êáé <literal>"cpg"</literal> èá ðñÝðåé íá åðéëå÷èïýí ìå ôÝôïéï
ôñüðï þóôå íá ôáéñéÜæïõí ìå ôï ðñáãìáôéêü óýóôçìá áñ÷åßùí, áí êáé
äåí Ý÷ïõí óçìáóßá óôç óõãêåêñéìÝíç ðåñßðôùóç.</para>
<para>Ìå áõôü ôïí ôñüðï, èá äçìéïõñãçèåß ìéá íÝá êáôÜôìçóç
<literal>"a"</literal> ç ïðïßá åðéêáëýðôåé ôçí êáôÜôìçóç ôïõ
Vinum óå áõôÞ ôç óõóêåõÞ. Óçìåéþóôå üôé ç åíôïëÞ
<command>bsdlabel</command> èá åðéôñÝøåé áõôÞ ôçí åðéêÜëõøç ìüíï
áí ç êáôÜôìçóç ôïõ Vinum Ý÷åé åðéóçìáíèåß êáôÜëëçëá ìå fstype
<literal>"vinum"</literal>.</para>
</step>
<step>
<para>Áõôü åßíáé üëï! ÕðÜñ÷åé ðëÝïí ìéá øåõôï-êáôÜôìçóç
<literal>"a"</literal> óå êÜèå óõóêåõÞ ç ïðïßá Ý÷åé áíôßãñáöï ôïõ
ñéæéêïý ôüìïõ. Óõíßóôáôáé íá åðáëçèåýóåôå îáíÜ ôï áðïôÝëåóìá,
÷ñçóéìïðïéþíôáò ìéá åíôïëÞ üðùò ôçí ðáñáêÜôù:</para>
<screen>&prompt.root; <userinput>fsck -n /dev/<replaceable>devname</replaceable>a</userinput></screen>
</step>
</procedure>
<para>Èá ðñÝðåé íá èõìÜóôå üôé ïé èÝóåéò ôùí áñ÷åßùí ðïõ ðåñéÝ÷ïõí
ðëçñïöïñßåò åëÝã÷ïõ ðñÝðåé íá åßíáé ó÷åôéêÝò ùò ðñïò ôï ñéæéêü
óýóôçìá áñ÷åßùí ðïõ âñßóêåôáé óôï ôüìï ôïõ Vinum, êáé ï ïðïßïò
(êáôÜ ôçí äçìéïõñãßá êáéíïýñéïõ ñéæéêïý ôüìïõ Vinum) ìðïñåß íá ìçí
ôáéñéÜæåé ìå ôï ñéæéêü óýóôçìá áñ÷åßùí ðïõ åßíáé åíåñãü ôç äåäïìÝíç
óôéãìÞ. Èá ðñÝðåé éäéáßôåñá íá öñïíôßóåôå ôá áñ÷åßá
<filename>/etc/fstab</filename> êáé
<filename>/boot/loader.conf</filename>.</para>
<para>Óôçí åðüìåíç åðáíåêêßíçóç, ï êþäéêáò åêêßíçóçò èá ðñÝðåé íá
åíôïðßóåé ôéò êáôÜëëçëåò ðëçñïöïñßåò åëÝã÷ïõ áðü ôï íÝï (Vinum)
ñéæéêü óýóôçìá áñ÷åßùí êáé íá äñÜóåé êáôÜëëçëá. Óôï ôÝëïò ôçò
äéáäéêáóßáò áñ÷éêïðïßçóçò ôïõ ðõñÞíá, êáé ìåôÜ ôçí áíáããåëßá üëùí
ôùí óõóêåõþí, ôï ìÞíõìá ôï ïðïßï äåß÷íåé ôçí åðéôõ÷Þ ëåéôïõñãßá
ôïõ åã÷åéñÞìáôïò ìïéÜæåé ìå ôï ðáñáêÜôù:</para>
<screen>Mounting root from ufs:/dev/gvinum/root</screen>
</sect2>
<sect2>
<title>ÐáñÜäåéãìá Ñýèìéóçò Ñéæéêïý Ôüìïõ ìå Vinum</title>
<para>ÌåôÜ ôçí ñýèìéóç ôïõ ñéæéêïý ôüìïõ ìå ôï Vinum, ç Ýîïäïò ôçò
åíôïëÞò <command>gvinum l -rv root</command> èá ìïéÜæåé ìå ôçí
ðáñáêÜôù:</para>
<screen>
...
Subdisk root.p0.s0:
Size: 125829120 bytes (120 MB)
State: up
Plex root.p0 at offset 0 (0 B)
Drive disk0 (/dev/da0h) at offset 135680 (132 kB)
Subdisk root.p1.s0:
Size: 125829120 bytes (120 MB)
State: up
Plex root.p1 at offset 0 (0 B)
Drive disk1 (/dev/da1h) at offset 135680 (132 kB)
</screen>
<para>Ïé ôéìÝò ðïõ èá ðñÝðåé íá óçìåéþóåôå åßíáé ôï
<literal>135680</literal> ãéá ôçí áðüóôáóç (offset óå ó÷Ýóç ìå ôçí
êáôÜôìçóç <filename class="devicefile">/dev/da0h</filename>). Áõôü
ìåôáöñÜæåôáé óå 265 block ôùí 512 byte ãéá ôçí åíôïëÞ
<command>bsdlabel</command>. Ðáñüìïéá, ôï ìÝãåèïò ôïõ ñéæéêïý ôüìïõ
åßíáé 245760 ìðëïê ôùí 512 byte. Ôï <filename
class="devicefile">/dev/da1h</filename>, ôï ïðïßï ðåñéÝ÷åé ôï
äåýôåñï áíôßãñáöï ôïõ ñéæéêïý ôüìïõ, Ý÷åé óõììåôñéêÞ ñýèìéóç.</para>
<para>Ôï bsdlabel ãéá áõôÝò ôéò óõóêåõÝò èá ìïéÜæåé ìå ôï
ðáñáêÜôù:</para>
<screen>
...
8 partitions:
# size offset fstype [fsize bsize bps/cpg]
a: 245760 281 4.2BSD 2048 16384 0 # (Cyl. 0*- 15*)
c: 71771688 0 unused 0 0 # (Cyl. 0 - 4467*)
h: 71771672 16 vinum # (Cyl. 0*- 4467*)</screen>
<para>Ìðïñåßôå íá ðáñáôçñÞóåôå üôé ç ðáñÜìåôñïò
<literal>"size"</literal> ãéá ôçí øåõôï-êáôÜôìçóç
<literal>"a"</literal> ôáéñéÜæåé ìå ôçí ôéìÞ ðïõ äåßîáìå ðáñáðÜíù,
åíþ ç ôéìÞ ôçò ðáñáìÝôñïõ <literal>"offset"</literal> åßíáé ôï
Üèñïéóìá ôçò áðüóôáóçò áíÜìåóá óôçí êáôÜôìçóç Vinum
<literal>"h"</literal> êáé ôçò áðüóôáóçò áõôÞò ôçò êáôÜôìçóçò ìÝóá
óôç óõóêåõÞ (Þ ôï slice). Ðñüêåéôáé ãéá ìéá ôõðéêÞ ñýèìéóç ðïõ åßíáé
áðáñáßôçôç ãéá íá áðïöåõ÷èïýí ôá ðñïâëÞìáôá ðïõ ðåñéãñÜöçêáí óôï
<xref linkend="vinum-root-panic"/>. Ìðïñåßôå åðßóçò íá äåßôå üôé
ïëüêëçñç ç êáôÜôìçóç <literal>"a"</literal> ðåñéÝ÷åôáé áõôïýóéá
ìÝóá óôçí <literal>"h"</literal> ç ïðïßá êáé ðåñéÝ÷åé üëåò ôéò
ðëçñïöïñßåò Vinum ôçò óõóêåõÞò.</para>
<para>Óçìåéþóôå üôé óôï ðáñáðÜíù ðáñÜäåéãìá ç óõóêåõÞ ÷ñçóéìïðïéåßôáé
åî' ïëïêëÞñïõ áðü ôï Vinum, êáé äåí õðÜñ÷åé êÜðïéï êáôÜëïéðï ñéæéêÞò
êáôÜôìçóçò áðü ðáëéüôåñç ÷ñÞóç. Áõôü óõìâáßíåé åðåéäÞ ðñüêåéôáé ãéá
äßóêï ðïõ ÷ñçóéìïðïéÞèçêå áðü ôçí áñ÷Þ ùò ìÝñïò åíüò óõóôÞìáôïò
Vinum.</para>
</sect2>
<sect2>
<title>Áíôéìåôþðéóç ÐñïâëçìÜôùí</title>
<para>Óå ðåñßðôùóç ðñïâëÞìáôïò, èá ÷ñåéáóôåßôå êÜðïéá ìÝèïäï
áíôéìåôþðéóçò. Ç ðáñáêÜôù ëßóôá ðåñéÝ÷åé ìåñéêÜ áðü ôá ðéï
óõíçèéóìÝíá ðñïâëÞìáôá êáé ôéò ëýóåéò ôïõò.</para>
<sect3>
<title>Ï Êþäéêáò Åêêßíçóçò Öïñôþíåôáé, ÁëëÜ ôï Óýóôçìá äåí
Åêêéíåß</title>
<para>Áí ãéá ïðïéïäÞðïôå ëüãï ôï óýóôçìá äåí óõíå÷ßæåé ôçí åêêßíçóç,
èá ðñÝðåé íá äéáêüøåôå ôçí åêêßíçóç ìÝóá óôï ÷ñïíéêü äéÜóôçìá ôùí 10
äåõôåñïëÝðôùí ðïõ åìöáíßæåôáé ï öïñôùôÞò åêêßíçóçò, ðéÝæïíôáò ôï
ðëÞêôñï <keycap>space</keycap>. Ìðïñåßôå íá åîåôÜóåôå ôéò ôéìÝò
ôùí ìåôáâëçôþí ôïõ öïñôùôÞ
(üðùò ç <literal>vinum.autostart</literal>), ÷ñçóéìïðïéþíôáò ôçí
åíôïëÞ <command>show</command>, êáé íá ôéò áëëÜîåôå ìå ôéò åíôïëÝò
<command>set</command> Þ <command>unset</command>.</para>
<para>Áí ôï ìïíáäéêü ðñüâëçìá Þôáí ç áðïõóßá ôïõ áñèñþìáôïò
Vinum óôç ëßóôá ôçò áõôüìáôçò öüñôùóçò, áñêåß íá äþóåôå ôçí
åíôïëÞ <command>load geom_vinum</command>.</para>
<para>¼ôáí åßóôå Ýôïéìïò, ç åêêßíçóç ìðïñåß íá óõíå÷éóôåß ìå ôçí
åíôïëÞ <command>boot -as</command>. Ïé åðéëïãÝò
<option>-as</option> èá ïäçãÞóïõí ôïí ðõñÞíá íá ñùôÞóåé ãéá ôï
ñéæéêü óýóôçìá áñ÷åßùí ðïõ ðñüêåéôáé íá ðñïóáñôçèåß
(<option>-a</option>), êáé ç äéáäéêáóßá åêêßíçóçò èá óôáìáôÞóåé óå
êáôÜóôáóç åíüò ÷ñÞóôç (single user, ëüãù ôçò åðéëïãÞò
<option>-s</option>), üðïõ ç ðñïóÜñôçóç ôïõ ñéæéêïý óõóôÞìáôïò
åßíáé ìüíï ãéá áíÜãíùóç. Ìå ôïí ôñüðï áõôü, áêüìá êáé áí Ý÷åé
ðñïóáñôçèåß ìüíï Ýíá plex åíüò ôüìïõ ðïõ áðïôåëåßôáé áðü ðïëëÜ,
äåí õðÜñ÷åé êßíäõíïò íá äçìéïõñãçèåß áóõíÝðåéá äåäïìÝíùí ìåôáîý
ôùí plex.</para>
<para>Óôçí ðñïôñïðÞ ðïõ åìöáíßæåôáé ãéá ôï ñéæéêü óýóôçìá áñ÷åßùí ðïõ
ðñüêåéôáé íá ðñïóáñôçèåß, ìðïñåßôå íá åéóÜãåôå ïðïéáäÞðïôå
óõóêåõÞ ðåñéÝ÷åé Ýíá Ýãêõñï ñéæéêü óýóôçìá áñ÷åßùí. Áí ôï
<filename>/etc/fstab</filename> Ý÷åé ñõèìéóôåß óùóôÜ, ç ðñïåðéëïãÞ
èá åßíáé êÜôé óáí <literal>ufs:/dev/gvinum/root</literal>.
Ìéá ôõðéêÞ åíáëëáêôéêÞ ôïðïèåóßá èá ìðïñïýóå íá åßíáé ôï
<literal>ufs:da0d</literal>, ìéá õðïèåôéêÞ êáôÜôìçóç
ðïõ ðåñéÝ÷åé ôï ðáëéü (ðñéí ôï Vinum) ñéæéêü óýóôçìá áñ÷åßùí.
Áí ðñüêåéôáé íá ÷ñçóéìïðïéÞóåôå ìéá
áðü ôéò ôýðïõ <literal>"a"</literal> øåõôï-êáôáôìÞóåéò ðïõ åßíáé
óôçí ðñáãìáôéêüôçôá õðïäßóêïé ôçò ñéæéêÞò óõóêåõÞò ôïõ Vinum, èá
ðñÝðåé íá åßóôå ðñïóåêôéêüò, ãéáôß áí ÷ñçóéìïðïéåßôå mirror èá
ãßíåé ðñïóÜñôçóç ìüíï ôïõ åíüò ôìÞìáôïò ôçò óõóêåõÞò.
Áí ðñüêåéôáé íá ðñïóáñôÞóåôå áõôÞ ôç óõóêåõÞ áñãüôåñá ìå
äõíáôüôçôá åããñáöÞò-áíÜãíùóçò, åßíáé áðáñáßôçôï íá áöáéñÝóåôå ôá
õðüëïéðá plex ôïõ ñéæéêïý ôüìïõ ôïõ Vinum, êáèþò áõôÜ èá ðåñéÝ÷ïõí
äåäïìÝíá ðïõ äåí åßíáé óå óõã÷ñïíéóìü ìå ôçí êáôÜôìçóç ðïõ Ý÷åôå
Þäç ðñïóáñôÞóåé.</para>
</sect3>
<sect3>
<title>Öïñôþíåé Ìüíï ï Âáóéêüò Êþäéêáò Åêêßíçóçò</title>
<para>Áí ç öüñôùóç ôïõ <filename>/boot/loader</filename> äåí åßíáé
åðéôõ÷Þò, áëëÜ ï âáóéêüò êþäéêáò åêêßíçóçò (primary bootstrap)
öïñôþíåôáé (êÜôé ðïõ ìðïñåßôå íá äéáðéóôþóåôå åëÝã÷ïíôáò áí
åìöáíßæåôáé ìéá ðáýëá óôçí ðÜíù áñéóôåñÞ ãùíßá ôçò ïèüíçò êáôÜ ôï
áñ÷éêü óôÜäéï åêêßíçóçò), ìðïñåßôå íá ðñïóðáèÞóåôå íá äéáêüøåôå
ôç âáóéêÞ åêêßíçóç óå áõôü ôï óçìåßï ÷ñçóéìïðïéþíôáò ôï ðëÞêôñï
<keycap>space</keycap>. Ìå áõôü ôïí ôñüðï, ç åêêßíçóç èá
óôáìáôÞóåé óôï óôÜäéï äýï (äåßôå ôï <xref linkend="boot-boot1"/>).
Ìðïñåßôå åäþ íá ðñïóðáèÞóåôå íá åêêéíÞóåôå áðü ìéá åíáëëáêôéêÞ
êáôÜôìçóç, ð.÷. ôçí êáôÜôìçóç ðïõ ðåñéåß÷å ôï ñéæéêü óýóôçìá
áñ÷åßùí ðïõ ìåôáêéíÞóáôå áðü ôï <literal>"a"</literal> üôáí
îåêéíÞóáôå íá ÷ñçóéìïðïéåßôå ôï Vinum.</para>
</sect3>
<sect3 id="vinum-root-panic">
<title>Äåí Ãßíåôáé ÊáìéÜ Åêêßíçóç, ï Êþäéêáò Åêêßíçóçò Ðñïêáëåß
Panic</title>
<para>Áõôü ìðïñåß íá óõìâåß áí ï êþäéêáò åêêßíçóçò êáôáóôñáöåß
áðü ôçí åãêáôÜóôáóç ôïõ Vinum. Äõóôõ÷þò, ôï Vinum ôçí ôñÝ÷ïõóá
óôéãìÞ áöÞíåé ìüíï 4 KB åëåýèåñá óôçí áñ÷Þ ôçò êáôÜôìçóçò ôïõ
ðñéí áñ÷ßóåé íá ãñÜöåé ôéò ðëçñïöïñßåò ôçò åðéêåöáëßäáò ôïõ.
Ùóôüóï ôá óôÜäéá Ýíá êáé äýï êáèþò êáé ôï bsdlabel ðïõ
åíóùìáôþíåôáé áíÜìåóá ôïõò, ÷ñåéÜæïíôáé 8 KB. ¸ôóé, áí ìéá
êáôÜôìçóç Vinum îåêßíáãå óôçí èÝóç 0 ìÝóá óå Ýíá slice Þ äßóêï ðïõ
ðñïïñßæïíôáí ãéá åêêßíçóç, ç åãêáôÜóôáóç ôïõ Vinum èá êáôÝóôñåöå
ôïí êþäéêá åêêßíçóçò.</para>
<para>Ìå ôïí ßäéï ôñüðï, áí ç ðáñáðÜíù êáôÜóôáóç åðéäéïñèùèåß ãéá
ðáñÜäåéãìá îåêéíþíôáò áðü Ýíá CD <quote>Fixit</quote> êáé
åðáíåãêáèéóôþíôáò ôïí êþäéêá åêêßíçóçò ìå ôç âïÞèåéá ôçò åíôïëÞò
<command>bsdlabel -B</command> (üðùò ðåñéãñÜöåôáé óôï <xref
linkend="boot-boot1"/>), ï êþäéêáò åêêßíçóçò èá êáôáóôñÝøåé ôçí
åðéêåöáëßäá ôïõ Vinum, ôï ïðïßï äåí èá ìðïñåß ðëÝïí íá åíôïðßóåé
ôïõò äßóêïõò ôïõ. Áí êáé ôï ðáñáðÜíù äåí êáôáóôñÝöåé ôá äåäïìÝíá
ñõèìßóåùí Þ ôá ðñáãìáôéêÜ äåäïìÝíá ðïõ õðÜñ÷ïõí óôïõò ôüìïõò (êáé
ç áíÜêôçóç ôïõò åßíáé äõíáôÞ áí äþóåôå îáíÜ áêñéâþò ôéò ßäéåò
ñõèìßóåéò óôï Vinum ìå ôéò áñ÷éêÝò óáò), ç êáôÜóôáóç äéïñèþíåôáé
áñêåôÜ äýóêïëá. Èá ðñÝðåé íá ìåôáêéíÞóåôå ïëüêëçñç ôçí êáôÜôìçóç
ôïõ Vinum ôïõëÜ÷éóôïí êáôÜ 4 KB þóôå íá ìçí õðÜñ÷åé óýãêñïõóç
ìåôáîý ôçò åðéêåöáëßäáò ôïõ Vinum êáé ôïõ êþäéêá åêêßíçóçò.</para>
</sect3>
</sect2>
</sect1>
</chapter>