From: Russell Coker <russell@coker.com.au>
To: linux-btrfs@vger.kernel.org
Subject: Re: raid1 inefficient unbalanced filesystem reads
Date: Sat, 29 Jun 2013 19:41:31 +1000 [thread overview]
Message-ID: <201306291941.32127.russell@coker.com.au> (raw)
In-Reply-To: <kqki3l$nmr$1@ger.gmane.org>
On Sat, 29 Jun 2013, Martin <m_btrfs@ml1.co.uk> wrote:
> Mmmm... I'm not sure trying to balance historical read/write counts is
> the way to go... What happens for the use case of an SSD paired up with
> a HDD? (For example an SSD and a similarly sized Raptor or enterprise
> SCSI?...) Or even just JBODs of a mishmash of different speeds?
>
> Rather than trying to balance io counts, can a realtime utilisation
> check be made and go for the least busy?
It would also be nice to be able to tune this. For example I've got a RAID-1
array that's mounted noatime, hardly ever written, and accessed via NFS on
100baseT. It would be nice if one disk could be spun down for most of the
time and save 7W of system power. Something like the --write-mostly option of
mdadm would be good here.
Also it should be possible for a RAID-1 array to allow faster reads for a
single process reading a single file if the file in question is fragmented.
--
My Main Blog http://etbe.coker.com.au/
My Documents Blog http://doc.coker.com.au/
next prev parent reply other threads:[~2013-06-29 9:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-28 13:59 raid1 inefficient unbalanced filesystem reads Martin
2013-06-28 15:34 ` Josef Bacik
2013-06-28 15:39 ` Hugo Mills
2013-06-28 15:56 ` Duncan
2013-06-28 16:25 ` Martin
2013-06-28 16:55 ` George Mitchell
2013-06-28 17:04 ` Josef Bacik
2013-06-28 17:45 ` Martin
2013-06-29 9:41 ` Russell Coker [this message]
2013-06-29 14:04 ` Martin
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