LVM2: problems with snapshots

Hello all,

i am new with LVM and related topics. After reading the Linux LVM howto i decided to use lvm an a machine which serves different data for our users.

After using it for a while i came to this site:

http://c.mills.ctru.auckland.ac.nz/Samba/XfsAclWinAuth.html

Inspired from the details to the "MicroBackups", i intend to do the same. I customized the script to fit our needs.

I create the directories /mnt/snapshots/{data,home} and want to have that every half hour from 7am until 7pm a snapshot is created an mounted on a directory which reflects the date/time of creation.

The directory structe then is:

/mnt/snapshot/data/20070520
|

 +--0700
 +--0730
 +...
 +...
 +--1830
 +--1900
/mnt/snapshot/data/20070521
 |
 +--0700
 +--0730
 +...
 +...
 +--1830
 +--1900

The same for the other shares and valid for a maximum of three days. If the snapshot has expired (reached the age of 3 day) it has to be unmounted and removed (the snapshot and the mount point).

The filesystem on these shares are XFS.

After creating a couple of snapshots and mounting them accordingly the machine freezes. Samba was unusable, login was able. But also a "shutdown -r now" does not work. The machine hung. Only reset helps out.

First i thought it is may a problem of XFS. I setup another machine for testing purposes with ext3. But the same occurs.

The system is:

Debian SID
Kernel 2.6.11
LVM2

Is the snapshot feature not intended for this what i do/want or have i a fault in thinking?

Any help/hint is much appreciated.

Best regards,
Micha Holzmann

Der Horizont vieler Menschen ist ein Kreis mit Radius Null,
und das nennen sie ihren Standpunkt