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188 lines
6.4 KiB
Plaintext
188 lines
6.4 KiB
Plaintext
=head1 NAME
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lvm2create_initrd - create initrd image for booting to root\-on\-LVM2
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=head1 SYNOPSIS
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B<lvm2create_initrd> [ B<-h|--help> ] [ B<-v|--verbose> ] [ B<-c|--lvmconf> I</path/to/lvm.conf> ] [ B<-m|--modules> "I<module1 module2 ...>" ] [ B<-e|--extra> "I<file1 file2 ...>" ] [ B<-r|--raid> "I</dev/md1 /dev/md2 ...>" ]
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[ B<-R|--raidconf> I</path/to/mdadm.conf> ] [ B<-M|--makedev> I<style> ]
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=head1 DESCRIPTION
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lvm2create_initrd creates an initial ramdisk (initrd) image suitable for booting to system that has an LVM2 volume as its root filesystem.
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To boot to such a setup, you'll
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either need a bootloader that understands LVM2 volumes, or you'll need a
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filesystem on a regular volume to act as a boot partition (typically mounted
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on /boot).
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The resulting initrd image is fairly full-featured. It can harbor and load
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kernel modules, start MD devices, and boot to a shell to perform rescue
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operations.
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=head2 Booting to your initrd Image:
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The filesystem image created is an ext2fs filesystem, hence your kernel must have
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ext2fs built into it statically in order to boot to the image.
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Once you create your initrd image, you must pass the correct options to the kernel when
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you boot using it. Your kernel command line should look something like this:
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B<root=/dev/ram0 lvm2root=/dev/rootvg/root [ lvm2rescue ]>
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of course there may be other options.
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=over
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=item B<root=/dev/ram0>
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This option is required. It tells the kernel that the root filesystem should initially
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be set to the ramdisk (/dev/ram0).
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=item B<lvm2root=/dev/rootvg/root>
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This option is also required. It tells the initrd image which LVM2 device the root filesystem is located on.
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=item B<lvm2rescue>
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Causes the initrd image to run a shell prior to mounting the root filesystem. This is
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helpful in disaster situations where your initrd image is accessible, but there is
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a problem with the root filesystem (corrupted image, incorrect device setup, etc.). This
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option is (of course) optional.
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=back
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=head1 OPTIONS
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Most of parameters that can be set via command-line options can also be set
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via environment variables. Options specified on the command-line always take
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precedence.
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=over
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=item B<-h|--help>
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Display short help text and exit. If used, other options are ignored.
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=item B<-v|--verbose>
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Turn on extra verbosity for debugging, etc.
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=item B<-c|--lvmconf> I</path/to/lvm.conf>
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Specify an lvm.conf file to include in the image. This is useful if you have
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special device filters or other options you wish to use during the initrd
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stage. If this option is not
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included, then a lvm.conf file is created that contains only the current
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device filter from an B<lvm dumpconfig>. This can also be set via the B<$LVMCONF>
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environment variable.
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=item B<-m|--modules> "I</path/to/module1.ko /path/to/module2.ko ...>"
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Specify modules to include and plug in during the initrd phase. This option
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takes a quoted, space-separated list of modules. Full pathnames are required.
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These modules are loaded into the kernel early in the initrd phase of the boot
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process. The current modprobe.conf file is also copied to the initrd image
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as well. This can also be specified via the B<$MODULES> environment variable.
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=item B<-e|--extra> "I</path/to/file1 /path/to/file2 ...>"
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Extra files that should be included in the initrd image. These files will be
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copied to the same location in the initrd image that they are in the current
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filesystem. Again full pathnames are required. This can also be specified via
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the B<$EXTRAFILES> environment variable.
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=item B<-r|--raid> "I</dev/md1 /dev/md2...>"
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RAID devices to be started prior to scanning for LVM2 volume groups. If this
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option is used then then B<mdadm> program must be installed. This can also be
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specified via the B<$RAID> environment variable.
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=item B<-R|--raidconf> "I</path/to/mdadm.conf>"
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Location of a mdadm.conf file to include. If this is not specified, then no
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files are included, and any devices specified with the B<-r> option above
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must have minor numbers that match their superblock values. This can also be
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specified via the B<$RAIDCONF> environment variable.
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=item B<-M|--makedev> I<style>
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Set MAKEDEV invocation style. The script currently supports 3 styles of
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MAKEDEV programs I<debian>, I<redhat> and I<gentoo>. The default is I<debian>.
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Set to I<redhat> if using the RedHat/Fedora binary MAKEDEV program. I<gentoo>
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has the same binary but in /sbin instead of /dev. Please send a bug report to
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maintainer if your distribution doesn't work with any of the current options.
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=back
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=head1 ENVIRONMENT VARIABLES
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Most of the options to this script can be set via environment variables. In
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situations where both are set, then the command-line options take precedence.
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=over
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=item B<$LVMCONF>
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Same as -c option.
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=item B<$MODULES>
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Same as -m option.
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=item B<$EXTRAFILES>
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Same as -e option.
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=item B<$RAID>
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Same as -r option.
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=item B<$RAIDCONF>
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Same as -R option.
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=item B<$MAKEDEV>
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Same as -M option.
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=item B<$BASICDEVICES>
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Overrides the default value of $BASICDEVICES in the script (which is "std consoleonly fd"). These values are passed to the B<MAKEDEV> program to create device
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entries in the initrd image.
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=item B<$BLOCKDEVICES>
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Overrides the default value of $BLOCKDEVICES in the script (which is "md hda hdb hdc hdd sda sdb sdc sdd"). This value is passed to the B<MAKEDEV> program to
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create device entries in the initrd image.
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=item B<$BINFILES>
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Overrides the default value of $BINFILES (which is "/lib/lvm-200/lvm /bin/bash /bin/busybox /sbin/pivot_root"). The difference between using this and adding
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a file to the $EXTRAFILES list above is that libraries that these depend upon are also included. You can still use $EXTRAFILES to achieve the same effect, but
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you must resolve library dependencies yourself.
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=item B<$INITRDSIZE>
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Force a particular size for your initrd image. The default is to total up the size of
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the included files and to add 512K as a buffer.
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=back
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=head1 BUGS
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I don't like having to specify a -M option to set the MAKEDEV style, but I know
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of no way to reliably detect what type of MAKEDEV is being used. We'll probably
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have to add other MAKEDEV styles in the future as this script is tested on
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other distributions.
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=head1 AUTHORS
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The script was originally written by Miguel Cabeca, with significant
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improvements by Jeffrey Layton. Comments, bug reports and patches should be
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sent to Jeffrey Layton at S<B<jtlayton@poochiereds.net>>.
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=head1 SEE ALSO
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B<MAKEDEV>(8), B<mdadm>(8), B<busybox>(8), B<lvm.conf>(5)
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