On Thu, Apr 6, 2017 at 10:31 AM, Gionatan Danti <g.danti@assyoma.it> wrote:

I'm seeking some advice for a new virtualization system (KVM) on top of LVM. The goal is to take agentless backups via LVM snapshots.

In short: what you suggest to snapshot a quite big (8+ TB) volume? Classic LVM (with old snapshot behavior) or thinlvm (and its new snapshot method)?

I found classic LVM snapshots to suffer terrible performance. I switched to BTRFS as a result, until LVM thin pools became a real thing, and I happily switched back.

I expect this depends on exactly what access patterns you have, how many accesses will happen during the time the snapshot is held, and whether you are using spindles or flash. Still, even with some attempt to be objective and critical... I think I would basically never use classic LVM snapshots for any purpose, ever.