[linux-lvm] Very slow i/o after snapshotting

Micky mickylmartin at gmail.com
Tue Jul 9 08:26:51 UTC 2013

> What do you mean by weekly snapshots?
> If you mean old-style snapshots not thin-ones, many snapshots with single
> origin LV then how many snapshots are you keeping around?

I meant, running lvcreate ---snapshot, copying the data with dd or pv
and then removing the snapshot.

> If you have N snapshots up to (N+1)*chunksize is written for every write.

It is only one snapshot. A fresh one is created and after use, it's removed.

> Also if this setup is used on HDDs the seektime may be relevant as well.
> Old style snapshots were not meant for long term use and should be used
> while snapshot is copied over to permanent location.

Makes sense. But the snapshots exist no more than just few hours for every LV.

> You may be better off using thin-snapshots. Otherwise the solution is
> dumping old snapshots or moving over to tape, whatever, just do not keep
> more of them.

Sounds like not much of an option since I don't have thin pools.
Haven't had much success with them.

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