"cannot allocate memory" when trying to do a snapshot?
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:
# free
total used free shared buffers cached
Mem: 512204 492212 19992 0 297784 17864
-/+ buffers/cache: 176564 335640
Swap: 3145720 0 3145720I've searched the list, and a similar cases appeared on the list in 2002/2003, most without any reply - but it was LVM1 / 2.4.x times.
Signature · 1 line
Tomasz Chmielewski
Quoted 10 lines · Tomasz Chmielewski
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
Quoted 7 lines
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?
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 4 lines · Tomasz Chmielewski
Some more info on that.
Apparently, this whole snapshotting thing is not very stable, and there are bugs in it.
This whole snapshotting thing is a known and fixed bug. I opened a bug about it in RH's bugzilla about a year ago but am unable to log back in there to find it specifically for you. Search for bugs reported by anyone @interlinx.bc.ca. Try the word "kcopy" in the bug if there are too many listed.
Cheers,
b.
Signature · 3 lines
My other computer is your Microsoft Windows server. Brian J. Murrell
Quoted 9 lines · Brian J. Murrell
Quoted 2 lines · Tomasz Chmielewski
Some more info on that.
Apparently, this whole snapshotting thing is not very stable, and there are bugs in it.This whole snapshotting thing is a known and fixed bug. I opened a bug about it in RH's bugzilla about a year ago but am unable to log back in there to find it specifically for you. Search for bugs reported by anyone @interlinx.bc.ca. Try the word "kcopy" in the bug if there are too many listed.
Looks like it's here:
https://bugzilla.redhat.com/show_bug.cgi?id=208172
Let's see if upgrading the kernel helps...
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 4 lines · Tomasz Chmielewski
Looks like it's here:
Yup. That's the one my bug 191531 was dup'd to.
Quoted 1 line
Let's see if upgrading the kernel helps...
Let us know.
b.
Signature · 3 lines
My other computer is your Microsoft Windows server. Brian J. Murrell
Quoted 10 lines · Brian J. Murrell
Quoted 3 lines · Tomasz Chmielewski
Looks like it's here:
Yup. That's the one my bug 191531 was dup'd to.
Quoted 1 line
Let's see if upgrading the kernel helps...
Let us know.
It looks that it helped.
However, now it's possible to create a snapshot that is no longer possible to remove...
See my other thread ("how much memory does LVM need? oom-killer comes").
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org