From mboxrd@z Thu Jan  1 00:00:00 1970
From: Lars Marowsky-Bree <lmb@suse.com>
Subject: Clustered RAID1 performance
Date: Thu, 30 May 2013 11:59:55 +0200
Message-ID: <20130530095955.GE11926@suse.de>
Reply-To: device-mapper development <dm-devel@redhat.com>
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Hi all,

we see a significant performance hit when mirroring is used for a cLVM2
LV.

That's clearly due to the performance overhead of bouncing to user-space
(and worse, to the network) for locking etc.

I wonder if consideration has been given to how this could be improved?
Using the in-kernel DLM and holding locks for regions the local node
writes to for longer, exclusive locks while noone is reading,
parallelizing the resync ...? How is the long-term perspective for this
given the dm-raid/md raid stuff?

Before we go drafting I wanted to ask for ideas that are already
floating around ;-) Anyone working on this?


Regards,
    Lars

-- =

Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffe=
r, HRB 21284 (AG N=FCrnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde