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From: Steve McIntyre <smcintyre@software.plasmon.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Snapshots (overheads and 2.6 kernel status)
Date: Mon, 29 Nov 2004 15:16:49 +0000	[thread overview]
Message-ID: <20041129151630.GD1506@software.plasmon.com> (raw)
In-Reply-To: <37E80E80B681A24B8F768D607373CA80010A5454@largo.campus.ncl.ac.uk>

On Mon, Nov 29, 2004 at 03:08:50PM -0000, C R Ritson wrote:
>Does anybody know how much overhead is involved in keeping a snapshot of
>an active volume (for 24 hours)? I am currently running LVM1 (waiting
>for snapshots in LVM2/device mapper) and am making a snapshot of my user
>volumes overnight. These are left available for 24 hours in the hope
>that users who damage a file will be able to get "yesterday's copy" from
>the snapshot without us needing to restore from tape. There is obviously
>some overhead involved, but does anyone know how much?

It can be quite significant, depending on your workload. I'm using
snapshots in a similar way, and I saw performance drop by a factor of
2 (or more) on our main NFS server. It's very useful to have the
snapshot, so we live with it.

-- 
Steve McIntyre, Plasmon                       smcintyre@software.plasmon.com
 
"C++ ate my sanity" -- Jon Rabone

      reply	other threads:[~2004-11-29 15:16 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-11-29 15:08 [linux-lvm] Snapshots (overheads and 2.6 kernel status) C R Ritson
2004-11-29 15:16 ` Steve McIntyre [this message]

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