From: Steven Haigh <netwiz@crc.id.au>
To: Felipe Franciosi <felipe.franciosi@citrix.com>
Cc: "Xen-devel@lists.xensource.com" <Xen-devel@lists.xensource.com>
Subject: Re: Xen disk write slowness in kernel 3.8.x
Date: Wed, 03 Apr 2013 22:42:10 +1100 [thread overview]
Message-ID: <515C1592.1090102@crc.id.au> (raw)
In-Reply-To: <9F2C4E7DFB7839489C89757A66C5AD620899E9@LONPEX01CL03.citrite.net>
On 03/04/13 22:36, Felipe Franciosi wrote:
> Based on what you said later, your raid stripe size is 128KB. When you plug /dev/md3 to your guest, you will be going through blkback/blkfront which only support 44KB per request.
This is interesting. The default size for a RAID5/6 via mdadm these days
is 512Kb.
> So can I ask what is the "task that is going on"?
> I mean, what is your workload and how does it look like (in terms of reads/writes, (a)sync and size)?
The load is mostly sequential writes. Samba + NFS shares mainly. Files
are usually 300Mb -> 10Gb. Its mostly writes, with occasional reads.
Interestingly, I get 220Mb/sec+ reads - but only ~50Mb/sec writes via
the DomU.
--
Steven Haigh
Email: netwiz@crc.id.au
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299
next prev parent reply other threads:[~2013-04-03 11:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-03 2:05 Xen disk write slowness in kernel 3.8.x Steven Haigh
2013-04-03 2:14 ` Steven Haigh
2013-04-03 11:36 ` Felipe Franciosi
2013-04-03 11:42 ` Steven Haigh [this message]
2013-04-03 12:29 ` Felipe Franciosi
2013-04-03 13:26 ` Steven Haigh
2013-04-03 14:30 ` Felipe Franciosi
2013-04-03 14:48 ` Steven Haigh
2013-04-09 6:53 ` Steven Haigh
2013-04-16 14:39 ` Felipe Franciosi
2013-04-17 7:52 ` Steven Haigh
2013-04-18 13:10 ` Felipe Franciosi
2013-04-19 2:12 ` Steven Haigh
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