From mboxrd@z Thu Jan  1 00:00:00 1970
From: Phillip Susi <psusi@cfl.rr.com>
Subject: Re: create lvm2 snapshot will take a long time while
 large IO on origin lv(till large IO ends)
Date: Thu, 29 Apr 2010 13:31:16 -0400
Message-ID: <4BD9C264.7040501@cfl.rr.com>
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Cc: Busby <chaimvy@gmail.com>
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On 4/28/2010 11:24 PM, Busby wrote:
> it seems the vgs suspend because the lvcreate cmd don't unlock the
> flock, but why the lvcreating of snapshot lv will be suspended while the
> origin is on big data IO?

Because when creating a snapshot it tries to flush any dirty buffers so
that the origin is in a consistent state at the time the snapshot is
created.  This is done to minimize the chance that the filesystem on the
snapshot will be corrupt.