[linux-lvm] 15 snapshot limit?

[Larry Dickson]

Hi all,

With a 768 GB logical volume in a 2235 GB volume group, and 4 GB of memory,
I try to set up lots of snapshots (of 45 or 50 GB each) and can't get past
15. Sometimes I'll succeed in generating more than 15 COWs in /dev/mapper,
but lvdisplay never shows more than 15 snapshots in the "LV snapshot status
source of" listing under the parent volume. I searched and found 15
snapshots mentioned in a couple places like
wiki.samba.org/index.php/Shadow_Copies_with_Snapshots - but nothing really
authoritative.

Is there really such a limit? Or is it a memory requirement - I seem to
remember so many MB memory per GB of storage, but can't find that either.
Versions are (variants of) lvm2-2.02.38, device-mapper-1.02.26,
kernel-smp-2.6.20 (64 bit).

TIA,

Larry Dickson
Cutting Edge Networked Storage
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