Tomasz Chmielewski schrieb:
I have a server with ~1.5T PV, on which I have several logial volumes
(LVs).
I decided to do a snapshot for five of these LVs, and it succeeded, but
only few times.
dom-dc1 san1 owi-ao 8.00G
dom-oss1 san1 owi-ao 16.00G
dom-sql1 san1 owi-ao 8.00G
dom-sql1-2 san1 owi-ao 50.00G
dom-ts1 san1 owi-ao 16.00G
For each of the LVs, I made 5G snapshots.
I could make three snapshots for all of them, but the fourth snapshot
failed for some LVs (in all, I could only make 18 * 5GB snapshots).
Why?
I'm using Debian Etch, with its 2.6.18 64 bit kernel.
The machine has 512 MB RAM, and 3 GB swap:
Some more info on that.
Apparently, this whole snapshotting thing is not very stable, and there
are bugs in it.
I just played a bit more with creating snapshots.
Below, although creating a snapshot fails, a new logical volume is created:
# lvcreate -L100G -s -n backup-snapshot /dev/san1/backup
File descriptor 3 left open
File descriptor 5 left open
File descriptor 7 left open
device-mapper: reload ioctl failed: Cannot allocate memory
Failed to suspend origin backup
# lvs
File descriptor 3 left open
File descriptor 5 left open
File descriptor 7 left open
LV VG Attr LSize Origin Snap%
Move Log Copy%
backup san1 -wi-ao 628.28G
backup-snapshot san1 -wi-d- 100.00G
(...)
So, if it fails, at least it shouldn't create any phantom volumes.
Does lvm snapshotting work any better with newer kernels?
--
Tomasz Chmielewski
http://wpkg.org
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