Dave wrote: > Hi Patrick, et al. > > Thanks for your comments! > I've been doing some testing on this topic, and encountering a bit of strange > behavior which seems to confirm the murkiness with switching VGs between hosts. > Please bear with my lengthy description, as I'm trying to be as clear as possible. > I really need to work this out. > > THE TEST: > > Hosts are P10 (primary node) and P11 (backup node) > VG is activated on P10 and fs is mounted. To test a switch to P11, I deactivate the > VG on P10, but DO NOT run vgexport (following your suggestion). I then, run > vgimport on P11 (but P11 reports it already knows about the VG - that's fine), and > then run an activate. However, when I try to run an e2fsck on the fs, I get the > following error: > > /sbin/e2fsck: No such device or address while trying to open /dev/tux-ao/app > Possibly non-existent or swap device? > > However, the device does exist, and looks identical to the one on P10: > [P11]$ ls -l /dev/tux-ao/app > brw-rw---- 1 root disk 58, 14 Dec 6 14:46 /dev/tux-ao/app > > I was able to fix the problem by putting vgexport back into the mix. In this case, > I export the VG from P10 and then after an import on P11 I was able to run e2fsck > and mount successfully. > > Also, this (unknown VG) message is somewhat common in pvscan, if a vgexport is not > performed: > >> pvscan -- inactive PV "/dev/sdk" is associated to unknown VG "tux-ao" (run > vgscan) > > > Here is another clear example of some unexpected behavior (at least to me)... > 1. status when $vg on P11 successful - notice the status of ACTIVE on P11 and > EXPORTED on P10 > > [P11]$ sudo pvscan > pvscan -- reading all physical volumes (this may take a while...) > ... > pvscan -- ACTIVE PV "/dev/sdk" of VG "tux-ao" [27.09 GB / 9.09 GB free] > > [P10]$ sudo pvscan > pvscan -- reading all physical volumes (this may take a while...) > ... > pvscan -- inactive PV "/dev/sdk" is in EXPORTED VG "tux-ao" [27.09 GB / 9.09 GB > free] > > Then... > 2. status after $vg is deactivated on P11 and activated on P10 (no vgexport run on > P11 before activation on P10) - Notice the "unknown VG" message on P10!!! > > [P11]$ sudo pvscan > pvscan -- reading all physical volumes (this may take a while...) > ... > pvscan -- inactive PV "/dev/sdk" of VG "tux-ao" [27.09 GB / 9.09 GB free] > > [P10]$ sudo pvscan > pvscan -- reading all physical volumes (this may take a while...) > ... > pvscan -- inactive PV "/dev/sdk" is associated to unknown VG "tux-ao" (run vgscan) > > Then... > 3. Then, when I tried an activation on P10 I get no joy at all (ie. cannot perform > operations on the logical volume), despite the fact that it exists: > [P10]$ ls -l /dev/tux-ao/app > brw-rw---- 1 root disk 58, 14 Dec 6 15:04 /dev/tux-ao/app > > /sbin/e2fsck: No such device or address while trying to open /dev/tux-ao/app > Possibly non-existent or swap device? > > Is this simply flakey behavior with LVM 1.0.8 ? > > We have several VGs on the machine, and sometimes we need to move one or two at a > time. LVM (v1) seems to have trouble here, at least without vgexport. Anyone know > what might be happening behind the scenes to cause this behavior? It's looking to > me like I really do need vgexport to make things work the way we want. > > Thanks again for helping me to clarify this situation. It's rather worrying that the two nodes seem to be reading different data from the same disks. I can't remember off-hand whether lvm1 does direct-io when it updates metadata, possibly not. In which case you might have to upgrade to lvm2 (which does). lvm1 is /not/ a clustering tool ;-) -- patrick _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
