recipe for LVM1 -> LVM2 on a stock FC1 system?
Bill Rugolsky Jr.
brugolsky at telemetry-investments.com
Fri Jan 2 07:34:25 UTC 2004
On Thu, Jan 01, 2004 at 07:54:14AM -0500, Robert P. J. Day wrote:
> in a nutshell, is there a recipe for taking a stock, LVM1-based, FC1 box,
> and moving up to LVM2? while changing as little else as possible, and
> still being in a position to upgrade to the 2.6 kernel afterwards? given
> that the first step of patching the kernel for DM support doesn't really
> work cleanly, i'm leery of pushing forward until i know what should
> have happened at this step.
First a warning: this is not for the faint-of-heart. Have a rescue CD
handy, and back up essential files (or at least put them on a non-LVM
partition)! I am not responsible if your system ends up unbootable.
Well, the version of DM in the Fedora kernel is not terribly useful.
It's from an older -ac kernel, and uses the old (v1) ioctl() interface.
The latest version of the interface (v4) used in the 2.6 kernel is
available from Joe Thornber's patchset. See the end of this message for
information on applying the patches to FC1 kernels.
As for packages, you need these or later versions from FC development:
initscripts-7.43-1
device-mapper-1.00.07-1
lvm2-2.00.08-1
lvm-1.03-17
mkinitrd-3.5.15.1-1
Beware: Apparently, mkinitrd-3.5.16.1 was broken. You can
get mkinitrd-3.5.15.1-2 from people.redhat.com/arjanv/2.6
Make the directory /etc/lvm:
mkdir /etc/lvm
You will also need to temporarily force /sbin/mkinitrd to use LVM2,
using something like:
--- /sbin/mkinitrd 2003-12-05 21:25:12.000000000 -0500
+++ /var/tmp/mkinitrd 2004-01-01 09:02:51.729458000 -0500
@@ -373,12 +373,6 @@
# If we use LVM, include lvm-mod
if [ -z "$nolvm" ]; then
- if [ -f /proc/lvm/global ]; then
- if grep -q '^VG:' /proc/lvm/global ; then
- findmodule -lvm-mod
- fi
- fi
-
if [ -x /sbin/dmsetup ]; then
dmout=$(/sbin/dmsetup ls)
if [ "$dmout" != "No devices found" ]; then
@@ -446,8 +440,7 @@
elif ! echo $rootdev | cut -c1-6 |grep -q "LABEL=" ; then
rootdev=$(echo "readlink $rootdev" | /sbin/nash --quiet)
major=`ls -l $rootdev | sed -e "s/.* \\([0-9]\+\\), *[0-9]\+.*/\\1/"`
- [ "$major" != "58" ] || root_lvm=1
- if echo $rootdev |grep -q /dev/mapper 2>/dev/null ; then root_lvm2=1 ; fi
+ root_lvm2=1
fi
rootfs=$(awk '{ if ($1 !~ /^[ \t]*#/ && $2 == "/") { print $3; }}' $fstab)
@@ -456,9 +449,6 @@
# in case the root filesystem is modular
findmodule -${rootfs}
-if [ -n "$root_lvm" ]; then
- findmodule -lvm-mod
-fi
if [ -n "$root_lvm2" ]; then
findmodule -dm-mod
fi
Then you can do
KVER=2.6.0-1.21 # whatever
mount --bind /var/tmp/mkinitrd /sbin/mkinitrd
rpm -ivh kernel-$KVER.i686.rpm
umount /sbin/mkinitrd
or, if you've already installed the kernel:
rm -f /boot/initrd-$KVER.img
/var/tmp/mkinitrd -v /boot/initrd-$KVER.img $KVER
Verify that dm-mod.o was included in the initrd.
You will have the problem that the LVM2 tools will not overwrite
device files in, e.g., the /dev/vg0/ directory; it will only overwrite symlinks.
(Why? I don't know.)
One possibility is to move these files elsewhere, e.g., /dev/lvm1/vg0/,
and create symlinks, before rebooting.
mkdir /dev/lvm1
cp -a /dev/vg0 /dev/lvm1
cd /dev/vg0 && ln -sf ../lvm1/vg0/* .
ls -l
Check that they are all symlinks.
Alternatively, modify rc.sysinit to remove the files from your VG directories
first. (I have not tested this!):
--- /etc/rc.d/rc.sysinit 2003-12-05 19:22:54.000000000 -0500
+++ /etc/rc.d/rc.sysinit 2004-01-01 11:15:17.179458000 -0500
@@ -349,6 +349,9 @@
/bin/rm -f /dev/mapper/control
echo "mkdmnod" | /sbin/nash --quiet >/dev/null 2>&1
if [ -e /dev/mapper/control -a -x /sbin/lvm ]; then
+ /sbin/lvm vgscan 2>/dev/null \
+ | sed -n -e 's!^.*Found volume group "\([^"]\{1,\}\)".*$!/dev/\1!p' \
+ | xargs -r rm -rf
action $"Setting up Logical Volume Management:" /sbin/lvm vgscan --mknodes && /sbin/lvm vgchange -a y
fi
fi
N.B.: These hacks are for a one-way trip to LVM2. If you plan on
occasionally booting LVM1, you'll hit the same problem again when
going back to LVM2, and will want to look more seriously at the problem.
There is one final step, that I forgot to mention before (sorry), which
is that you need to fastboot, in order to avoid running fsck (which will
otherwise fail, because it can't find the root filesystem device on
the (read-only) root filesystem:
touch /fastboot
If you are moving up to 2.6, be sure to examine the documents on
migrating to 2.6, check the contents of your /etc/modprobe.conf, etc.
I'll reiterate: it helps to have a rescue CD handy when doing these
things.
That ends the root-on-lvm2 instructions.
Now on the issue of building the 2.4 kernel with current DM,
take a look at what is modified by the DM patches:
[2.4.23-pre7-dm3]$ diffstat *.patch
Documentation/Configure.help | 14
MAINTAINERS | 7
arch/mips64/kernel/ioctl32.c | 17
arch/parisc/kernel/ioctl32.c | 17
arch/ppc64/kernel/ioctl32.c | 17
arch/s390x/kernel/ioctl32.c | 15
arch/sparc64/kernel/ioctl32.c | 17
arch/x86_64/ia32/ia32_ioctl.c | 17
drivers/md/Config.in | 10
drivers/md/Makefile | 35
drivers/md/dm-daemon.c | 115 +++
drivers/md/dm-daemon.h | 29
drivers/md/dm-exception-store.c | 677 +++++++++++++++++++
drivers/md/dm-io.c | 370 ++++++++++
drivers/md/dm-io.h | 86 ++
drivers/md/dm-ioctl.c | 1420 ++++++++++++++++++++++++++++++++++++++--
drivers/md/dm-linear.c | 125 +++
drivers/md/dm-log.c | 311 ++++++++
drivers/md/dm-log.h | 112 +++
drivers/md/dm-raid1.c | 1304 ++++++++++++++++++++++++++++++++++++
drivers/md/dm-snapshot.c | 1246 ++++++++++++++++++++++++++++++++++-
drivers/md/dm-snapshot.h | 158 ++++
drivers/md/dm-stripe.c | 258 +++++++
drivers/md/dm-table.c | 792 ++++++++++++++++++++--
drivers/md/dm-target.c | 188 +++++
drivers/md/dm.c | 1133 +++++++++++++++++++++++++++++++
drivers/md/dm.h | 177 ++++
drivers/md/kcopyd.c | 680 ++++++++++++++++++-
drivers/md/kcopyd.h | 47 +
drivers/md/lvm.c | 9
fs/buffer.c | 31
fs/jbd/journal.c | 10
fs/reiserfs/super.c | 2
fs/super.c | 138 +++
include/linux/device-mapper.h | 104 ++
include/linux/dm-ioctl.h | 237 ++++++
include/linux/fs.h | 5
include/linux/jbd.h | 2
include/linux/mempool.h | 31
include/linux/vmalloc.h | 1
kernel/ksyms.c | 3
mm/Makefile | 4
mm/filemap.c | 11
mm/mempool.c | 299 ++++++++
mm/vmalloc.c | 19
45 files changed, 10101 insertions(+), 199 deletions(-)
It should not be very difficult to merge; one ought to be able to
simply replace the files
drivers/md/{Config.in,Makefile,dm-*,k*,lvm.c}
include/linux/device-mapper.h
include/linux/dm-ioctl.h
from a patched Marcelo kernel, and merge the others by hand.
mempool.[ch] ought to be approximately the same.
The only other large change is the one to fs/super.c, from
00005.patch, which replaces the use of fsync_dev() with
fsync_dev_lockfs(). This is a cleanup, and is likely optional.
Without 00005.patch, there are likely no significant differences
outside of
drivers/mod/{dm-*,kcopyd.*}
include/linux/dm-ioctl.h
include/linux/device-mapper.h
on x86. [The ioctl() mapping for bi-arch systems can be ignored.]
If that is the case, one can construct a drop-in replacement for
dm-mod.o (on x86).
Or one could politely ask Dave Jones if he would replace the
device-mapper code in the next FC1 kernel. :-)
Regards,
Bill Rugolsky
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