On Thu, Apr 17, 2008 at 03:58:09PM +0100, Stephane Chazelas wrote: > Hiya, > > I hope you could help me on this: > > > in short: > > is it possible to create a snapshot LV of an original LV > but in a different volume group? No, not with LVM. > > or alternatively, what's the best way to bring up a LV in a VG > that is missing a PV (as in a disk crash) if that LV has all its > extents on still sane PVs? vgchange -P -ay If you have 2 disks, you better mirror them to be completely HA on the spindle side of things and avoid any such config hassle, potentially leaving you with lost data. Heinz > > > in long: > > basically, this is what I would like to do: > > I have two disks, not as much as I would like, and I want: > - to have 100GB of data mirrored (using Linux software raid > (mdadm)) on 2 disks so that it survives disk crashs > - to make a number of frequent snapshots of that data to > be able to restore things in case of human errors. > - (and I also want to have some "striped" storage space for > worthless data). > > BUT, I don't want to have the snapshot volumes mirrored. > > My initial idea was to have 2 volume groups: a "safe" one with > only one /dev/md0 PV and an "unsafe" one with the striped LVs > and the snapshots. > > However I couldn't find how to create snapshots of the LVs in > "safe" into the "unsafe" VG. It seems to me that it should be > possible, shouldn't it? > > Anyway, then I merged the two "safe" and "unsafe" VGs into one > "vol" VG. Now I can make snapshots of the LV physically located > on /dev/md0 into the "unsafe" area. > > But if one of the disks fails, /dev/md0 will still be available > but the "vol" VG won't be able to come up because of the other > missing PVs. > > If such a thing happen, I can happily live with the missing > snapshots and "unsafe" storage for a while until I buy a > replacement HD, but how should I do about making sure that the > /dev/md0 filesystem is still available in the mean time? > > Or is there a more straightforward way to achieve this that I > haven't thought of? > > TIA, > Stephane > > _______________________________________________ > 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/ =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat GmbH Consulting Development Engineer Am Sonnenhang 11 Storage Development 56242 Marienrachdorf Germany Mauelshagen@RedHat.com PHONE +49 171 7803392 FAX +49 2626 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- _______________________________________________ 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/
