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Date: Thu, 21 Apr 2016 11:11:53 +0100
From: Alasdair G Kergon <agk@redhat.com>
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Subject: Re: [linux-lvm] Why LVM metadata locations are not properly aligned
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To: LVM general discussion and development <linux-lvm@redhat.com>

On Thu, Apr 21, 2016 at 12:08:55PM +0800, Ming-Hung Tsai wrote:
> However, it's hard to achieve that if the PV is busy running IO. 

So flush your data in advance of running the snapshot commands so there is only
minimal data to sync during the snapshot process itself.

> The major overhead is LVM metadata IO.

Are you sure?  That would be unusual.  How many copies of the metadata have you
chosen to keep?  (metadata/vgmetadatacopies)  How big is this metadata?  (E.g.
size of /etc/lvm/backup/<vgname> file.)

Alasdair