Limitation: only < 32 snapshots possible

Hi together,

i create 5 LV's (e.g. play1..n) and therefore, i created 10 snapshots for each LV. After 32 snapshots (should 5*10 = 50 snapshots), i got the following error:
"device-mapper: reload ioctl failed: Cannot allocate memory"

My versions (on debian etch):

   xentor:/etc/lvm# lvm version
     LVM version:     2.02.07 (2006-07-17)
     Library version: 1.02.08 (2006-07-17)
     Driver version:  4.7.0

I looked arround and found http://sources.redhat.com/lvm2/wiki/FrequentlyAskedQuestions (last topic on page):

* > Known problem - will be partially solved by new DM-IO interface.
* > But anyway, current snapshot implementation is not properly designed for such type of operation (many snapshots will significantly slow down all IO).

QUESTION: Is this limitiation fixed in the current version 2.02.24 from ftp://sources.redhat.com/pub/lvm2

Thanks for helping

regards

Danny

BTW: I want to clone (means create LVMs-snapshot) about 40 xen vm's running on 4 xen-server .. therefore it would nice to use the LVM2-snapshot-feature (instead of GFS/OCFS2).

These are limitations of the existing kernel implementation, not userspace.

Alasdair

[email protected]

Hi Alasdair,

is there a kernel patch to fix this limiation ?

regards

Danny