Error creating snapshot, "Cannot allocate memory"
I have a volume group that is 1.4 TB, with a volume that is 400 GB. I currently have three 50 GB snapshots of that volume. When I try to create a fourth, I get the following error:
bash-2.05a# lvcreate -L 50G -s -n snap_home1_20021202 /dev/home/home1 lvcreate -- WARNING: the snapshot will be automatically disabled once it gets full
lvcreate -- INFO: using default snapshot chunk size of 64 KB for "/dev/home/snap_home1_20021202"
lvcreate -- ERROR "Cannot allocate memory" creating VGDA for "/dev/home/snap_home1_20021202" in kernel
After some experimenting, I found that I could create a snapshot that is 36 GB or smaller, but anything larger than 36 GB fails with the above error. The volume group has 386 GB free.
Any thoughts? I looked through the changelog and mailing list archives and couldn't find anything similar.
Other possibly useful bits of info:
OS: Red Hat 7.3 kernel: 2.4.18-18.7.xsmp LVM: 1.0.3-4 (Red Hat RPM)
Jason
Quoted 11 lines · On Mon, Dec 02, 2002 at 02:32:23PM -0800, [email protected] wrote:
I have a volume group that is 1.4 TB, with a volume that is 400 GB. I currently have three 50 GB snapshots of that volume. When I try to create a fourth, I get the following error:
bash-2.05a# lvcreate -L 50G -s -n
snap_home1_20021202/dev/home/home1lvcreate -- WARNING: the snapshot will be automatically disabled once it gets full
lvcreate -- INFO: using default snapshot chunk size of 64 KB for "/dev/home/snap_home1_20021202"
lvcreate -- ERROR "Cannot allocate memory" creating VGDA for "/dev/home/snap_home1_20021202" in kernel
You don't have enough kernel virtual memory to hold the snapshot exception table in core :(
Install more RAM.
We have planned to reduce the amount of RAM needed to hold such tables in LVM2/device-mapper next year.
Quoted 22 lines
After some experimenting, I found that I could create a snapshot that is 36 GB or smaller, but anything larger than 36 GB fails with the above error. The volume group has 386 GB free.
Any thoughts? I looked through the changelog and mailing list archives and couldn't find anything similar.
Other possibly useful bits of info:
OS: Red Hat 7.3 kernel: 2.4.18-18.7.xsmp LVM: 1.0.3-4 (Red Hat RPM)Jason
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Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
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Heinz Mauelshagen Sistina Software Inc.
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[email protected] +49 2626 141200
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-Quoted 14 lines · Heinz J . Mauelshagen
Quoted 11 lines · On Mon, Dec 02, 2002 at 02:32:23PM -0800, [email protected] wrote:
I have a volume group that is 1.4 TB, with a volume that is 400 GB. I currently have three 50 GB snapshots of that volume. When I try to create a fourth, I get the following error:
bash-2.05a# lvcreate -L 50G -s -n
snap_home1_20021202/dev/home/home1lvcreate -- WARNING: the snapshot will be automatically disabled once it gets full
lvcreate -- INFO: using default snapshot chunk size of 64 KB for "/dev/home/snap_home1_20021202"
lvcreate -- ERROR "Cannot allocate memory" creating VGDA for "/dev/home/snap_home1_20021202" in kernel
Quoted 3 lines
You don't have enough kernel virtual memory to hold the snapshot exception table in core :(
Install more RAM.
I've seen this error as well. In a machine with 1GB memory and the only processes
running were NFS and samba. Just how much memory does it need ?
Quoted 2 lines
We have planned to reduce the amount of RAM needed to hold such tables in LVM2/device-mapper next year.
That would be nice.
JonB
Quoted 10 lines · Jon Bendtsen
Quoted 4 lines · Heinz J . Mauelshagen
You don't have enough kernel virtual memory to hold the snapshot exception table in core :(
Install more RAM.I've seen this error as well. In a machine with 1GB memory and the only processes
running were NFS and samba. Just how much memory does it need ?
Indeed, my server has 2 GB of RAM and 1 GB of swap, of which free reports only a few hundred MB in use.
Jason
Quoted 7 lines · Jason Heiss
Quoted 6 lines · Jon Bendtsen
Quoted 4 lines · Heinz J . Mauelshagen
You don't have enough kernel virtual memory to hold the snapshot exception table in core :(
Install more RAM.
Quoted 7 lines
Quoted 4 lines
I've seen this error as well. In a machine with 1GB memory and the only processes
running were NFS and samba. Just how much memory does it need ?Indeed, my server has 2 GB of RAM and 1 GB of swap, of which free reports only a few hundred MB in use.
Hmmm...
vmalloc() fails to allocate kernel virtual memory. That's why you get the error. Could well be a constraint in vmalloc() in general or in the Redhat kernel you use.
Have you tried using a 2.4.20 vanilla kernel and were able to reproduce this (enough free RAM presumed).
Quoted 9 lines
Jason
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read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Signature · 15 lines
Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
[email protected] +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-