<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=US-ASCII" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> Stuart D. Gathman wrote: <blockquote cite="midPine.LNX.4.44.0805012041160.26700-100000@bmsred.bmsi.com" type="cite"> <pre wrap="">ZZZZOn Thu, 1 May 2008, Charles Marcus wrote: </pre> <blockquote type="cite"> <pre wrap="">In Gerry's scenario here, if the snapshot volume had NOT been on a ram disk, would he have had the problem he had or not? </pre> </blockquote> <pre wrap=""> Here is the snip from Fedora/RHEL for activating the VG containing the root filesystem (note: kernel modules and lvm command are contained in initrd filesystem, and do not depend on /lib/modules/...): ... echo "Loading dm-mod.ko module" insmod /lib/dm-mod.ko echo "Loading dm-mirror.ko module" insmod /lib/dm-mirror.ko echo "Loading dm-zero.ko module" insmod /lib/dm-zero.ko echo "Loading dm-snapshot.ko module" insmod /lib/dm-snapshot.ko echo Making device-mapper control node mkdmnod mkblkdevs echo Scanning logical volumes lvm vgscan --ignorelockingfailure </pre> </blockquote> So right ^^^here^^^ is where we need to test if old snapshot was read-only or read-write (how to do that? grep vgdisplay -v for some value?) So maybe something like this?: set removemissing flag false if old snapshot is the only PV missing: --if old snapshot was read-write: ------stop boot sequence ------show user some info about old snapshot ------prompt whether to remove the old snapshot from the VG so it can be activated ------if response yes: ----------set removemissing flag true ------else ----------alert user that manual action is required to correct problem related to old snapshot before VG can be activated ----------abort boot --elsif old snapshot was read-only: ------set removemissing flag true if removemissing flag true: ----vgreduce --removemissing VG PV(old snapshot) Gerry <blockquote cite="midPine.LNX.4.44.0805012041160.26700-100000@bmsred.bmsi.com" type="cite"> <pre wrap="">echo Activating logical volumes lvm vgchange -ay --ignorelockingfailure rootvg ... This will fail if any of the physical volumes are missing. More logic in initrd is required to boot with missing PVs. So yes, a ram disk is guaranteed to be missing on reboot, and thus to fail in the RH/Fedora distros. There is no problem taking snapshots of the root fs otherwise. If there is a robust way to reduce missing PVs automagically in the above script from initrd, Fedora could use the contribution. </pre> </blockquote> </body> </html>