283 lines
12 KiB
Text
283 lines
12 KiB
Text
<!-- $FreeBSD$ -->
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<!DOCTYPE article PUBLIC "-//FreeBSD//DTD DocBook V4.1-Based Extension//EN" [
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<!ENTITY % articles.ent PUBLIC "-//FreeBSD//ENTITIES DocBook FreeBSD Articles Entity Set//EN">
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%articles.ent;
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]>
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<article>
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<articleinfo>
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<title>&iomegazip; Drives</title>
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<authorgroup>
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<author>
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<firstname>Jason</firstname>
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<surname>Bacon</surname>
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<affiliation>
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<address><email>acadix@execpc.com</email></address>
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</affiliation>
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</author>
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</authorgroup>
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<legalnotice id="trademarks" role="trademarks">
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&tm-attrib.freebsd;
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&tm-attrib.adaptec;
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&tm-attrib.iomega;
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&tm-attrib.microsoft;
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&tm-attrib.opengroup;
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&tm-attrib.general;
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</legalnotice>
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</articleinfo>
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<sect1>
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<title>&iomegazip; Drive Basics</title>
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<para>&iomegazip; disks are high capacity, removable, magnetic disks, which can be
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read or written by ZIP drives from IOMEGA corporation. ZIP disks are
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similar to floppy disks, except that they are much faster, and have a
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much greater capacity. While floppy disks typically hold 1.44
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megabytes, ZIP disks are available in two sizes, namely 100 megabytes
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and 250 megabytes. ZIP drives should not be confused with the
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super-floppy, a 120 megabyte floppy drive which also handles traditional
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1.44 megabyte floppies.</para>
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<para>IOMEGA also sells a higher capacity, higher performance drive called
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the &jaz;/JAZZ drive. Jaz drives come in 1 gigabyte and 2 gigabyte
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sizes.</para>
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<para>ZIP drives are available as internal or external units, using one of
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three interfaces:</para>
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<orderedlist>
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<listitem>
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<para>The SCSI (Small Computer Standard Interface) interface is the
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fastest, most sophisticated, most expandable, and most expensive
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interface. The SCSI interface is used by all types of computers
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from PC's to RISC workstations to minicomputers, to connect all
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types of peripherals such as disk drives, tape drives, scanners, and
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so on. SCSI ZIP drives may be internal or external, assuming your
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host adapter has an external connector.</para>
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<note>
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<para>If you are using an external SCSI device, it is important
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never to connect or disconnect it from the SCSI bus while the
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computer is running. Doing so may cause file-system damage on the
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disks that remain connected.</para>
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</note>
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<para>If you want maximum performance and easy setup, the SCSI
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interface is the best choice. This will probably require adding a
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SCSI host adapter, since most PC's (except for high-performance
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servers) do not have built-in SCSI support. Each SCSI host adapter
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can support either 7 or 15 SCSI devices, depending on the
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model.</para>
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<para>Each SCSI device has its own controller, and these
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controllers are fairly intelligent and well standardized, (the
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second `S' in SCSI is for Standard) so from the operating system's
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point of view, all SCSI disk drives look about the same, as do all
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SCSI tape drives, etc. To support SCSI devices, the operating
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system need only have a driver for the particular host adapter, and
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a generic driver for each type of device, i.e. a SCSI disk driver,
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SCSI tape driver, and so on. There are some SCSI devices that can
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be better utilized with specialized drivers (e.g. DAT tape drives),
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but they tend to work OK with the generic driver, too. It is just
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that the generic drivers may not support some of the special
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features.</para>
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<para>Using a SCSI zip drive is simply a matter of determining which
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device file in the <filename>/dev</filename> directory represents
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the ZIP drive. This can be determined by looking at the boot
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messages while FreeBSD is booting (or in
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<filename>/var/log/messages</filename> after booting), where you
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will see a line something like this:</para>
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<programlisting>da1: <IOMEGA ZIP 100 D.13> Removable Direct Access SCSI-2 Device</programlisting>
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<para>This means that the ZIP drive is represented by the file
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<filename>/dev/da1</filename>.</para>
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</listitem>
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<listitem>
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<para>The IDE (Integrated Drive Electronics) interface is a low-cost
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disk drive interface used by many desktop PC's. Most IDE devices
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are strictly internal.</para>
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<para>Performance of IDE ZIP drives is comparable to SCSI ZIP drives.
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(The IDE interface is not as fast as SCSI, but ZIP drives
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performance is limited mainly by the mechanics of the drive, not by
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the bus interface.)</para>
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<para>The drawback of the IDE interface is the limitations it imposes.
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Most IDE adapters can only support 2 devices, and IDE interfaces are
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not typically designed for the long term. For example, the original
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IDE interface would not support hard disks with more than 1024
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cylinders, which forced a lot of people to upgrade their hardware
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prematurely. If you have plans to expand your PC by adding another
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disk, a tape drive, or scanner, you may want to invest in a SCSI
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host adapter and a SCSI ZIP drive to avoid problems in the
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future.</para>
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<para>IDE devices in FreeBSD are prefixed with an <literal>a</literal>.
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For example, an IDE hard disk might be
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<filename>/dev/ad0</filename>, an IDE (ATAPI) CDROM might be
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<filename>/dev/acd1</filename>, and so on.</para>
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</listitem>
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<listitem>
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<para>The parallel port interface is popular for portable external
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devices such as external ZIP drives and scanners, because virtually
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every computer has a standard parallel port (usually used for
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printers). This makes things easy for people to transfer data
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between multiple computers by toting around their ZIP drive.</para>
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<para>Performance will generally be slower than a SCSI or IDE ZIP
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drive, since it is limited by the speed of the parallel port.
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Parallel port speed varies considerably between various computers,
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and can often be configured in the system BIOS. Some machines will
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also require BIOS configuration to operate the parallel port in
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bidirectional mode. (Parallel ports were originally designed only
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for output to printers)</para>
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</listitem>
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</orderedlist>
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</sect1>
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<sect1>
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<title>Parallel ZIP: The <devicename>vpo</devicename> Driver</title>
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<para>To use a parallel-port ZIP drive under FreeBSD, the
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<devicename>vpo</devicename> driver must be configured into the kernel.
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Parallel port ZIP drives also have a built-in SCSI controller. The vpo
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driver allows the FreeBSD kernel to communicate with the ZIP drive's
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SCSI controller through the parallel port.</para>
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<para>Since the vpo driver is not a standard part of the kernel (as of
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FreeBSD 3.2), you will need to rebuild the kernel to enable this device.
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The process of building a kernel is outlined in detail in the
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<ulink url="&url.books.handbook;/kernelconfig.html">&os; Handbook</ulink>.
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The following steps outline the process in brief for the
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purpose of enabling the vpo driver:</para>
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<orderedlist>
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<listitem>
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<para>Run <command>/stand/sysinstall</command>, and install the kernel
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source code on your system.</para>
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</listitem>
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<listitem>
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<para>Create a custom kernel configuration, that includes the
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driver for the vpo driver:</para>
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<screen>&prompt.root; <userinput>cd /sys/i386/conf</userinput>
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&prompt.root; <userinput>cp GENERIC MYKERNEL</userinput></screen>
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<para>Edit <filename>MYKERNEL</filename>, change the
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<literal>ident</literal> line to <literal>MYKERNEL</literal>, and
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uncomment the line describing the vpo driver.</para>
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<para>If you have a second parallel port, you may need to copy the
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section for <literal>ppc0</literal> to create a
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<literal>ppc1</literal> device. The second parallel port usually
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uses IRQ 5 and address 378. Only the IRQ is required in the config
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file.</para>
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<para>If your root hard disk is a SCSI disk, you might run into a
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problem with probing order, which will cause the system to attempt
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to use the ZIP drive as the root device. This will cause a boot
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failure, unless you happen to have a FreeBSD root file-system on
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your ZIP disk! In this case, you will need to <quote>wire
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down</quote> the root disk, i.e. force the kernel to bind a
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specific device to <filename>/dev/da0</filename>, the root SCSI
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disk. It will then assign the ZIP disk to the next available SCSI
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disk, e.g. <literal>/dev/da1</literal>. To wire down your SCSI hard
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drive as <literal>da0</literal>, change the line
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<programlisting>device da0</programlisting>
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to
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<programlisting>disk da0 at scbus0 target 0 unit 0</programlisting></para>
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<para>You may need to change the target above to match the SCSI ID of
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your disk drive. You should also wire down the scbus0 entry to your
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controller. For example, if you have an &adaptec; 15xx controller,
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you would change
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<programlisting>controller scbus0</programlisting>
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to
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<programlisting>controller scbus0 at aha0</programlisting></para>
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<para>Finally, since you are creating a custom kernel configuration,
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you can take the opportunity to remove all the unnecessary drivers.
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This should be done with a great deal of caution, and only if you
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feel confident about making modifications to your kernel
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configuration. Removing unnecessary drivers will reduce the kernel
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size, leaving more memory available for your applications. To
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determine which drivers are not needed, go to the end of the file
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<filename>/var/log/messages</filename>, and look for lines reading
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"not found". Then, comment out these devices in your config file.
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You can also change other options to reduce the size and increase
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the speed of your kernel. Read the section on rebuilding your kernel
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for more complete information.</para>
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</listitem>
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<listitem>
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<para>Now it is time to compile the kernel:</para>
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<screen>&prompt.root; <userinput>/usr/sbin/config MYKERNEL</userinput>
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&prompt.root; <userinput>cd ../../compile/MYKERNEL</userinput>
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&prompt.root; <userinput>make clean depend && make all install</userinput></screen>
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</listitem>
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</orderedlist>
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<para>After the kernel is rebuilt, you will need to reboot. Make sure the
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ZIP drive is connected to the parallel port before the boot begins. You
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should see the ZIP drive show up in the boot messages as device vpo0 or
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vpo1, depending on which parallel port the drive is attached to. It
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should also show which device file the ZIP drive has been bound to. This
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will be <filename>/dev/da0</filename> if you have no other SCSI disks in
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the system, or <filename>/dev/da1</filename> if you have a SCSI hard
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disk wired down as the root device.</para>
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</sect1>
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<sect1>
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<title>Mounting ZIP disks</title>
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<para>To access the ZIP disk, you simply mount it like any other disk
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device. The file-system is represented as slice 4 on the device, so for
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SCSI or parallel ZIP disks, you would use:</para>
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<screen>&prompt.root; <userinput>mount_msdos /dev/da1s4 /mnt</userinput></screen>
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<para>For IDE ZIP drives, use:</para>
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<screen>&prompt.root; <userinput>mount_msdos /dev/ad1s4 /mnt</userinput></screen>
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<para>It will also be helpful to update <filename>/etc/fstab</filename> to
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make mounting easier. Add a line like the following, edited to suit your
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system:
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<programlisting>/dev/da1s4 /zip msdos rw,noauto 0 0</programlisting>
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and create the directory <filename>/zip</filename>.</para>
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<para>Then, you can mount simply by typing
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<screen>&prompt.root; <userinput>mount /zip</userinput></screen>
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and unmount by typing
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<screen>&prompt.root; <userinput>umount /zip</userinput></screen></para>
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<para>For more information on the format of
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<filename>/etc/fstab</filename>, see &man.fstab.5;.</para>
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<para>You can also create a FreeBSD file-system on the ZIP disk using
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&man.newfs.8;. However, the disk will only be usable on a FreeBSD
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system, or perhaps a few other &unix; clones that recognize FreeBSD
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file-systems. (Definitely not &ms-dos; or &windows;.)</para>
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</sect1>
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</article>
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