[linux-lvm] Standard Linux Framework for Snapshot Notification

[Block Device]

Hi,

  I  want to know whether Linux provides any standard interface for
volume managers etc so that applications can register themselves to be
notified when a snapshot needs to be taken.
Something similar to VSS on Windows.

If there isnt any such interface how is consistency guaranteed for
application data when a snapshot is taken ? eg. How does one take
(consistent) snapshots of database instances w/o  first quiescing them
?

If this not the right place to ask this, can someone point me in the
right direction ?

Thanks & Regards
BD.