LVM2 migration on 2.4.24 troubles - prepare for 2.6

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Hello,

i tried to migrate my system to LVM2 on 2.4 before migration to 2.6 to avoid troubles with LVM. I got the newest device-mapper/LVM2 tools and installed them alongside with a patched kernel and dm-mod.

When i try to "vgchange -ay" with device-mapper/LVM2 i get all of my lv's except one! All my snapshots are also corrupt (I use snapshots intensively).

Back to LVM1 was no problem - everything running and Ok. On another machine without snapshots moving to dm/LVM2 on 2.4.24 was no problem.

Are there incompatibilities regarding snapshots with LVM1/2?

The lvm level 9 log of vgscan/vgchange is attached (bz2 compressed). Here comes the kernel output while activating with LVM2/dm:

$ rmmod lvm-mod
lvm -- Module successfully deactivated

$ modprobe dm-mod
device-mapper: 4.0.5-ioctl (2003-11-18) initialised: [email protected]

$ vgscan --mknodes
  Reading all physical volumes.  This may take a while...
  Found volume group "vg00" using metadata type lvm1
  Found volume group "vg01" using metadata type lvm1
  9 logical volume(s) in volume group "vg00" now active
  47 logical volume(s) in volume group "vg01" now active

$ vgchange -ay
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Invalid/corrupt snapshot
device-mapper: Could not create kcopyd client
device-mapper: error adding target to table
  0 logical volume(s) in volume group "vg00" now active
  15 logical volume(s) in volume group "vg01" now active

Regards
Axel Reinhold
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Yes - snapshots are implemented differently: the on-disk data is different.

Always drop snapshots before switching between LVM1 / LVM2.

Alasdair

[email protected]

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According to Alasdair G Kergon:

Dear Alasdair,

thanks for your answer. I use snapshots intensively. I currently have 6 monthly, 5 weekly and 7 daily snapshots active with a rotating algorithm.

Does the new implementation copy dirty blocks also in "all" active snapshots or is it now possible to use the cow-blocks "cross-snapshot"? I mean that a new dirty block is only copied into the oldest snapshot and all the other ones can use that one. NetApp's Filer does it this way.

Regards
Axel Reinhold

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