Hi Alexander,
LVM snapshots are meant to be used on the user visible raid1 LVs.
You found a bug allowing it to be used on its hidden legs.
Removing such per leg snapshot should be possible after the raid1 LV got
deactivated.
Heinz
On 10/23/2017 04:19 PM, Alexander 'Leo' Bergolth wrote:
Hi!
As the raid1 check of my two-drive LV recently reported a mismatch count
0, I did some forensics.
One experiment was to create a snapshot of one leg of the mirror and try
to mount the snapshot. This worked fine but unfortunately I cannot
remove the snapshot now!
lvm wants to remove the origin too:
-------------------- 8< --------------------
# lvremove vg_test/snap_leg_0
Do you really want to remove active origin logical volume vg_test/testlv_rimage_0 with 1 snapshot(s)? [y/n]: n
Logical volume vg_test/testlv_rimage_0 not removed.
-------------------- 8< --------------------
(I have added the full history of a test setup below.)
Could anyone provide a hint how to get rid of the snapshot?
(Maybe manually using dmsetup commands and metadata backup editing?)
Thanks,
--leo
-------------------- snip! --------------------
# lvcreate --type raid1 -m 1 -n testlv -L100m vg_test /dev/vdb /dev/vdc
Logical volume "testlv" created.
# lvcreate -s -L50m -n snap_leg_0 /dev/mapper/vg_test-testlv_rimage_0
Using default stripesize 64.00 KiB.
Rounding up size to full physical extent 52.00 MiB
Logical volume "snap_leg_0" created.
# lvremove vg_test/snap_leg_0
Do you really want to remove active origin logical volume vg_test/testlv_rimage_0 with 1 snapshot(s)? [y/n]: n
Logical volume vg_test/testlv_rimage_0 not removed.
# lvs -a -o+devices,lv_uuid
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert Devices LV UUID
root vg_sys -wi-ao---- 5.00g /dev/vda2(0) fqp4Np-mLyL-y0OS-nufS-0hsT-7ijc-lGD9Za
swap vg_sys -wi-ao---- 2.00g /dev/vda2(2048) uNG1ht-eOKQ-y8Ji-yWSU-ZkZS-ZTIe-1M82mW
var vg_sys -wi-ao---- 3.00g /dev/vda2(1280) nDwCsP-vn38-6AUb-Dqer-VkLv-QHs3-CfVNCR
snap_leg_0 vg_test swi-a-s--- 52.00m [testlv_rimage_0] 0.00 /dev/vdb(26) f5AXqK-lDNe-hNrO-AW7G-yFvl-ctxU-fivKQf
testlv vg_test rwi-a-r--- 100.00m 100.00 testlv_rimage_0(0),testlv_rimage_1(0) Av5Y8Z-NBTH-tfN2-hCbW-Sur0-ebGU-SHBlsk
[testlv_rimage_0] vg_test owi-aor--- 100.00m /dev/vdb(1) OJyEep-Lgfm-B20o-4rfl-d38O-QByz-8oBa5z
[testlv_rimage_1] vg_test iwi-aor--- 100.00m /dev/vdc(1) J4AP4p-Mhfo-4oPn-SOFP-CGAi-riyL-CFr1fk
[testlv_rmeta_0] vg_test ewi-aor--- 4.00m /dev/vdb(0) Hgd58x-5Z2C-phkD-cIvl-KbPB-UWPz-THyZ3h
[testlv_rmeta_1] vg_test ewi-aor--- 4.00m /dev/vdc(0) mvehrT-Ofci-nWpm-A43m-iBpl-YW1U-Z1Z9x4
# lvremove --select lv_uuid=f5AXqK-lDNe-hNrO-AW7G-yFvl-ctxU-fivKQf
Do you really want to remove active origin logical volume vg_test/testlv_rimage_0 with 1 snapshot(s)? [y/n]: n
Logical volume vg_test/testlv_rimage_0 not removed.
-------------------- snip! --------------------
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