Incorporate 12.2 Initial Configuration - Partition Layout into
2.7 Allocating Disk Space. Sponsored by: iXsystems
This commit is contained in:
Dru Lavigne
parent
4fe406539c
commit
35d930b925
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=44296
2 changed files with 98 additions and 140 deletions
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@ -1232,6 +1232,104 @@ Trying to mount root from cd9660:/dev/iso9660/FREEBSD_INSTALL [ro]...</screen>
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</mediaobject>
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</figure>
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<para>This section describes what to consider when laying
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out the disk partitions. It then demonstrates how to use both
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the Guided Partitioning and Manual Partitioning screens.</para>
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<sect2 xml:id="configtuning-initial">
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<title>Designing the Partition Layout</title>
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<indexterm><primary>partition layout</primary></indexterm>
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<indexterm>
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<primary><filename>/etc</filename></primary>
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</indexterm>
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<indexterm>
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<primary><filename>/var</filename></primary>
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</indexterm>
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<indexterm>
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<primary><filename>/usr</filename></primary>
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</indexterm>
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<para>When laying out file systems, remember that hard drives transfer data
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faster from the outer tracks to the inner. Thus, smaller
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and heavier-accessed file systems should be closer to the
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outside of the drive, while larger partitions like
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<filename>/usr</filename> should be placed toward the inner
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parts of the disk. It is a good idea to create partitions
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in an order similar to: <filename>/</filename>, swap,
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<filename>/var</filename>, and
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<filename>/usr</filename>.</para>
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<para>The size of the <filename>/var</filename> partition
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reflects the intended machine's usage. This partition is
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used to hold mailboxes, log files, and printer spools.
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Mailboxes and log files can grow to unexpected sizes
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depending on the number of users and how long log files are
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kept. On average, most users rarely need more than about a
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gigabyte of free disk space in
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<filename>/var</filename>.</para>
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<note>
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<para>Sometimes, a lot of disk space is required in
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<filename>/var/tmp</filename>. When new software is
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installed, the packaging tools
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extract a temporary copy of the packages under
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<filename>/var/tmp</filename>. Large software packages,
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like <application>Firefox</application>,
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<application>OpenOffice</application> or
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<application>LibreOffice</application> may be tricky to
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install if there is not enough disk space under
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<filename>/var/tmp</filename>.</para>
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</note>
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<para>The <filename>/usr</filename> partition holds many of
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the files which support the system, including the &os; Ports
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Collection and system source code. At least 2 gigabytes is
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recommended for this partition.</para>
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<para>When selecting partition sizes, keep the space
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requirements in mind. Running out of space in one partition
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while barely using another can be a hassle.</para>
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<indexterm>
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<primary>swap sizing</primary>
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</indexterm>
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<indexterm>
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<primary>swap partition</primary>
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</indexterm>
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<para>As a rule of thumb, the swap partition should be about
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double the size of physical memory (<acronym>RAM</acronym>).
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Systems with minimal <acronym>RAM</acronym> may perform
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better with more swap. Configuring too little swap can
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lead to inefficiencies in the <acronym>VM</acronym> page
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scanning code and might create issues later if more memory
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is added.</para>
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<para>On larger systems with multiple <acronym>SCSI</acronym>
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disks or multiple <acronym>IDE</acronym> disks operating
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on different controllers, it is recommended that swap be
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configured on each drive, up to four drives. The swap
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partitions should be approximately the same size. The
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kernel can handle arbitrary sizes but internal data
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structures scale to 4 times the largest swap partition.
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Keeping the swap partitions near the same size will allow
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the kernel to optimally stripe swap space across disks.
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Large swap sizes are fine, even if swap is not used much.
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It might be easier to recover from a runaway program before
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being forced to reboot.</para>
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<para>By properly partitioning a system, fragmentation
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introduced in the smaller write heavy partitions will not
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bleed over into the mostly read partitions. Keeping the
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write loaded partitions closer to the disk's edge will
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increase I/O performance in the partitions where it occurs
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the most. While I/O performance in the larger partitions
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may be needed, shifting them more toward the edge of the
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disk will not lead to a significant performance improvement
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over moving <filename>/var</filename> to the edge.</para>
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</sect2>
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<sect2 xml:id="bsdinstall-part-guided">
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<title>Guided Partitioning</title>
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@ -60,11 +60,6 @@
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<para>After reading this chapter, you will know:</para>
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<itemizedlist>
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<listitem>
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<para>How to efficiently work with file systems and swap
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partitions.</para>
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</listitem>
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<listitem>
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<para>The basics of <filename>rc.conf</filename> configuration
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and <filename>/usr/local/etc/rc.d</filename> startup
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@ -110,141 +105,6 @@
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</itemizedlist>
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</sect1>
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<sect1 xml:id="configtuning-initial">
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<title>Initial Configuration</title>
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<sect2>
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<title>Partition Layout</title>
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<indexterm><primary>partition layout</primary></indexterm>
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<indexterm>
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<primary><filename>/etc</filename></primary>
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</indexterm>
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<indexterm>
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<primary><filename>/var</filename></primary>
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</indexterm>
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<indexterm>
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<primary><filename>/usr</filename></primary>
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</indexterm>
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<sect3>
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<title>Base Partitions</title>
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<para>When laying out file systems with &man.bsdlabel.8; or
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&man.sysinstall.8;, remember that hard drives transfer data
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faster from the outer tracks to the inner. Thus, smaller
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and heavier-accessed file systems should be closer to the
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outside of the drive, while larger partitions like
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<filename>/usr</filename> should be placed toward the inner
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parts of the disk. It is a good idea to create partitions
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in an order similar to: <filename>/</filename>, swap,
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<filename>/var</filename>, and
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<filename>/usr</filename>.</para>
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<para>The size of the <filename>/var</filename> partition
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reflects the intended machine's usage. This partition is
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used to hold mailboxes, log files, and printer spools.
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Mailboxes and log files can grow to unexpected sizes
|
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depending on the number of users and how long log files are
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kept. On average, most users rarely need more than about a
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gigabyte of free disk space in
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<filename>/var</filename>.</para>
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<note>
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<para>Sometimes, a lot of disk space is required in
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<filename>/var/tmp</filename>. When new software is
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installed with &man.pkg.add.1;, the packaging tools
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extract a temporary copy of the packages under
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<filename>/var/tmp</filename>. Large software packages,
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like <application>Firefox</application>,
|
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<application>OpenOffice</application> or
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<application>LibreOffice</application> may be tricky to
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install if there is not enough disk space under
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<filename>/var/tmp</filename>.</para>
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</note>
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<para>The <filename>/usr</filename> partition holds many of
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the files which support the system, including the &os; Ports
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Collection and system source code. At least 2 gigabytes is
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recommended for this partition.</para>
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|
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<para>When selecting partition sizes, keep the space
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requirements in mind. Running out of space in one partition
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while barely using another can be a hassle.</para>
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<note>
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<para>The <literal>Auto-defaults</literal> partition sizer
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used by &man.sysinstall.8; will sometimes select smaller
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than adequate <filename>/var</filename> and
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<filename>/</filename> partitions. Partition wisely and
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generously.</para>
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</note>
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</sect3>
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<sect3 xml:id="swap-design">
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<title>Swap Partition</title>
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<indexterm>
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<primary>swap sizing</primary>
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</indexterm>
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<indexterm>
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<primary>swap partition</primary>
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</indexterm>
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<para>As a rule of thumb, the swap partition should be about
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double the size of physical memory (<acronym>RAM</acronym>)
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as the kernel's virtual memory (<acronym>VM</acronym>)
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paging algorithms are tuned to perform best when the swap
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partition is at least two times the size of main memory.
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Systems with minimal <acronym>RAM</acronym> may perform
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better with more swap. Configuring too little swap can
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lead to inefficiencies in the <acronym>VM</acronym> page
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scanning code and might create issues later if more memory
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is added.</para>
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<para>On larger systems with multiple <acronym>SCSI</acronym>
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disks or multiple <acronym>IDE</acronym> disks operating
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on different controllers, it is recommended that swap be
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configured on each drive, up to four drives. The swap
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partitions should be approximately the same size. The
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kernel can handle arbitrary sizes but internal data
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structures scale to 4 times the largest swap partition.
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Keeping the swap partitions near the same size will allow
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the kernel to optimally stripe swap space across disks.
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Large swap sizes are fine, even if swap is not used much.
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It might be easier to recover from a runaway program before
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being forced to reboot.</para>
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</sect3>
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<sect3>
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<title>Why Partition?</title>
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<para>Several users think a single large partition will be
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fine, but there are several reasons why this is a bad idea.
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First, each partition has different operational
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characteristics and separating them allows the file system
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to tune accordingly. For example, the root and
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<filename>/usr</filename> partitions are read-mostly, with
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few writes, while a lot of reads and writes could occur in
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<filename>/var</filename> and
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<filename>/var/tmp</filename>.</para>
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<para>By properly partitioning a system, fragmentation
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introduced in the smaller write heavy partitions will not
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bleed over into the mostly read partitions. Keeping the
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write loaded partitions closer to the disk's edge will
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increase I/O performance in the partitions where it occurs
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the most. While I/O performance in the larger partitions
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may be needed, shifting them more toward the edge of the
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disk will not lead to a significant performance improvement
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over moving <filename>/var</filename> to the edge. Finally,
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there are safety concerns. A smaller, neater root partition
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which is mostly read-only has a greater chance of surviving
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a bad crash.</para>
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</sect3>
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</sect2>
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</sect1>
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<sect1 xml:id="configtuning-core-configuration">
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<title>Core Configuration</title>
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