[linux-lvm] How to monitor and possibly autoextend snapshots

[marcin kaluza comarch pl]

Hi

Is there a way to get notified, when the snapshot fills up to a certain
level? i.e.  via dmsetup wait [] ? I looked for event numbers but couldn't
find any doc for them.
The best thing would be to make snapshots autoextensible when given a max
size and resize value (just like oracle tablespaces do), but I suppose
that would require much coding...
Any thoughts?

We're using lvm snapshots for samba shadow copies and database cloning,
but there's a problem with monitoring snapshots % of usage - now we just
have a daemon that polls lvdisplay periodically and extends the lv when
necessary. But this is unreliable - you have to either poll often or keep
enough of free space and still you can end up with a trashed snap.

Martin