Re: [Qemu-devel] [RFC] qemu snapshot enchancement

[Dietmar Maurer]

> If you've been using it for 4 years then it was without dm-thin, which is a 
> new
> snapshot mechanism that solves limitations of classic LVM snapshot
> volumes.  So if you're referring to inefficient LVM snapshots then that should
> be solvable now.

Are you sure this work on shared iSCSI devices (I have my doubts)?

Besides, we use RHEL6.3 kernel, and AFAIK dm-thin is still not marked stable 
there.

> Or is LVM a pain for other reasons?

a.) it only works on LVM (new solution works on any storage type)
b.) You need free space on the VG (almost every user configures LVM without 
leaving
any free space on the VG).
c.) you need to specify snapshot size in advance
d.) performance is bad on writes.

The new solution work perfectly on all storage types, works on shared storage, 
and
does not need any free space on the source storage.