[linux-lvm] kernel errors from a merging snapshot

[Lentes, Bernd]

Hi,

i have a /-filesystem residing on a lv. I also had a snapshot of that lv because I tried some software. After testing the software I merged the snapshot into the origin, by rebooting. It seemed to went fine.
Btw: how do I know when merging is finished ? Where can I see results from the merging ?
But in /var/log/messages I have error messages about a block device:

Oct 14 16:22:45 vm59093-4 kernel: [ 7.580247] Buffer I/O error on device dm-3, logical block 0
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580254] Buffer I/O error on device dm-3, logical block 1
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580258] Buffer I/O error on device dm-3, logical block 2
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580261] Buffer I/O error on device dm-3, logical block 3
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580264] Buffer I/O error on device dm-3, logical block 0
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580271] Buffer I/O error on device dm-3, logical block 9961471
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580274] Buffer I/O error on device dm-3, logical block 9961471
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580341] Buffer I/O error on device dm-3, logical block 0
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580345] Buffer I/O error on device dm-3, logical block 1

Dm-3 is the snapshot I merged (although I named it root-snapshot while creating, not root--snapshot !):

Dmsetup info says:

...
Name: vg_1-root--snapshot
State: ACTIVE
Read Ahead: 1024
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 3
Number of targets: 1
UUID: LVM-ZfsXYr9bkOt1d9bMNpcrn7MxH2aX6H0bhELCnywHd7rbddry6f63xtkk1vqs1hvv
...

The errors appeared during the reboot. Is that normal ?


Bernd

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Bernd Lentes

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[Mike Snitzer]

On Tue, Oct 14 2014 at 2:08pm -0400,

Post by Lentes, Bernd
Hi,
i have a /-filesystem residing on a lv. I also had a snapshot of that lv because I tried some software. After testing the software I merged the snapshot into the origin, by rebooting. It seemed to went fine.
Btw: how do I know when merging is finished ? Where can I see results from the merging ?

You can use lvm to see the merge in progress (via lvs). Or you can have
a look at the "How to determine when a merging is complete" section of
the kernel's Documentation/device-mapper/snapshot.txt

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580247] Buffer I/O error on device dm-3, logical block 0
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580254] Buffer I/O error on device dm-3, logical block 1
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580258] Buffer I/O error on device dm-3, logical block 2
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580261] Buffer I/O error on device dm-3, logical block 3
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580264] Buffer I/O error on device dm-3, logical block 0
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580271] Buffer I/O error on device dm-3, logical block 9961471
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580274] Buffer I/O error on device dm-3, logical block 9961471
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580341] Buffer I/O error on device dm-3, logical block 0
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580345] Buffer I/O error on device dm-3, logical block 1
...
Name: vg_1-root--snapshot
State: ACTIVE
Read Ahead: 1024
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 3
Number of targets: 1
UUID: LVM-ZfsXYr9bkOt1d9bMNpcrn7MxH2aX6H0bhELCnywHd7rbddry6f63xtkk1vqs1hvv
...
The errors appeared during the reboot. Is that normal ?

We replace the device that is being merged with the "error" target. So
any IO directly to the merging device will get errored out. But IIRC
that was fixed with an updated lvm2 (libdm) change to hide the device
from udev (udev rules were trying to read labels from the device via
blkid, etc).

Which distro and kernel are you using?

[Lentes, Bernd]

-----Ursprüngliche Nachricht-----
Gesendet: Dienstag, 14. Oktober 2014 23:07
An: Lentes, Bernd
Cc: LVM general discussion and development
Betreff: Re: kernel errors from a merging snapshot
On Tue, Oct 14 2014 at 2:08pm -0400,

Post by Lentes, Bernd
Hi,
i have a /-filesystem residing on a lv. I also had a snapshot of that lv

because I tried some software. After testing the software I merged the
snapshot into the origin, by rebooting. It seemed to went fine.

Post by Lentes, Bernd
Btw: how do I know when merging is finished ? Where can I see results

from the merging ?
You can use lvm to see the merge in progress (via lvs). Or you can have a
look at the "How to determine when a merging is complete" section of the
kernel's Documentation/device-mapper/snapshot.txt

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580247] Buffer I/O error on device

dm-3, logical block 0

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580254] Buffer I/O error on device

dm-3, logical block 1

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580258] Buffer I/O error on device

dm-3, logical block 2

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580261] Buffer I/O error on device

dm-3, logical block 3

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580264] Buffer I/O error on device

dm-3, logical block 0

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580271] Buffer I/O error on device

dm-3, logical block 9961471

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580274] Buffer I/O error on device

dm-3, logical block 9961471

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580341] Buffer I/O error on device

dm-3, logical block 0

Post by Lentes, Bernd
Oct 14 16:22:45 vm59093-4 kernel: [ 7.580345] Buffer I/O error on device

dm-3, logical block 1

Post by Lentes, Bernd
Dm-3 is the snapshot I merged (although I named it root-snapshot while
...
Name: vg_1-root--snapshot
State: ACTIVE
Read Ahead: 1024
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 3
Number of targets: 1
LVM-

ZfsXYr9bkOt1d9bMNpcrn7MxH2aX6H0bhELCnywHd7rbddry6f63xtkk1vqs1hv
v

Post by Lentes, Bernd
...
The errors appeared during the reboot. Is that normal ?

We replace the device that is being merged with the "error" target. So any
IO directly to the merging device will get errored out. But IIRC that was fixed
with an updated lvm2 (libdm) change to hide the device from udev (udev
rules were trying to read labels from the device via blkid, etc).
Which distro and kernel are you using?

SLES 11 SP3 64bit, kernel 3.0.76-0.11-default


Bernd

Helmholtz Zentrum München
Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH)
Ingolstädter Landstr. 1
85764 Neuherberg
www.helmholtz-muenchen.de
Aufsichtsratsvorsitzende: MinDir´in Bärbel Brumme-Bothe
Geschäftsführer: Prof. Dr. Günther Wess, Dr. Nikolaus Blum, Dr. Alfons Enhsen
Registergericht: Amtsgericht München HRB 6466
USt-IdNr: DE 129521671