[linux-lvm] unable to recover from degraded raid1 with thin pool

Alexander 'Leo' Bergolth leo at strike.wu.ac.at
Mon Oct 23 13:26:09 UTC 2017

On 10/20/2017 11:06 PM, Gionatan Danti wrote:
> Il 19-10-2017 13:45 Alexander 'Leo' Bergolth ha scritto:
>> On 10/17/2017 03:45 PM, Alexander 'Leo' Bergolth wrote:
>>> I just tested lv activation with a degraded raid1 thin pool.
>>> Unfortunately it looks like activation mode=degraded only works for
>>> plain raid1 lvs. If you add a thin pool, lvm won't activate it in
>>> degraded mode. (Unless you specify --activationmode partial, which is
>>> IMHO rather dangerous.)
>> Unfortunately I cannot even replace a faulty PV if a thin pool is
>> present.
> From you command history, I can see you are trying to remove the failed
> device (to re-add a good device later).
> Instead, can you try with lvconvert --repair or lvconvert --replace? Do
> they works?

lvconvert --repair doesn't work because there is also a linear LV
("boot") on this VG, which already has the error target assigned instead
of the missing PV:

-------------------- 8< --------------------
# lvconvert --repair /dev/vg_test/boot /dev/vdd
  WARNING: Disabling lvmetad cache for repair command.
  WARNING: Not using lvmetad because of repair.
  Couldn't find device with uuid 5ORr1v-kn3T-ROJW-quEg-0Lp5-3kdX-M3jr8S.
Attempt to replace failed RAID images (requires full device resync)?
[y/n]: y
  vg_test/boot has components with error targets that must be removed
first: vg_test/boot_rimage_1.
  Try removing the PV list and rerun. the command.
  Failed to remove the specified images from vg_test/boot.
  Failed to replace faulty devices in vg_test/boot.
-------------------- 8< --------------------

(But removing the missing PV doesn't work because of the Thin volume
which is considered as partial as described previously.)

lvconvert --replace also refuses to process bcause of the missing PV:
-------------------- 8< --------------------
# lvconvert --replace 5ORr1v-kn3T-ROJW-quEg-0Lp5-3kdX-M3jr8S
vg_test/Thin_tdata /dev/vdd
  Couldn't find device with uuid 5ORr1v-kn3T-ROJW-quEg-0Lp5-3kdX-M3jr8S.
  Cannot change VG vg_test while PVs are missing.
  Consider vgreduce --removemissing.
  Cannot process volume group vg_test
-------------------- 8< --------------------

e-mail   ::: Leo.Bergolth (at) wu.ac.at
fax      ::: +43-1-31336-906050
location ::: IT-Services | Vienna University of Economics | Austria

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