From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Gandalf Corvotempesta <gandalf.corvotempesta@gmail.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: agcount for 2TB, 4TB and 8TB drives
Date: Fri, 6 Oct 2017 08:38:03 -0700 [thread overview]
Message-ID: <20171006153803.GI7122@magnolia> (raw)
In-Reply-To: <CAJH6TXgShHj6UynrNAs8eG0ZRFz5gSGGY1ZARPSofsNibi0Grg@mail.gmail.com>
On Fri, Oct 06, 2017 at 10:46:20AM +0200, Gandalf Corvotempesta wrote:
> Hi to all,
> i'm new to XFS.
>
> Which is the proper agcount for 2TB, 4TB and 8TB drives (not part of any RAID) ?
>
> mkfs.xfs automatically choosen 4 AGs. Isn't this too low ?
No. Have a look at calc_default_ag_geometry in libxcmd/topology.c for
how we calculate the default AG count / size. 4TB single-disks and
smaller get 4 AGs; larger than that get 1AG per TB. RAID arrays are
different.
Semirelated question: for a solid state disk on a machine with high CPU
counts do we prefer agcount == cpucount to take advantage of the
high(er) iops and lack of seek time to increase parallelism?
(Not that I've studied that in depth.)
--D
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next prev parent reply other threads:[~2017-10-06 15:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-06 8:46 agcount for 2TB, 4TB and 8TB drives Gandalf Corvotempesta
2017-10-06 15:38 ` Darrick J. Wong [this message]
2017-10-06 16:18 ` Eric Sandeen
2017-10-06 22:20 ` Dave Chinner
2017-10-06 22:21 ` Eric Sandeen
2017-10-09 8:05 ` Avi Kivity
2017-10-09 11:23 ` Dave Chinner
2017-10-09 15:46 ` Avi Kivity
2017-10-09 22:03 ` Dave Chinner
2017-10-10 9:07 ` Avi Kivity
2017-10-10 22:55 ` Dave Chinner
2017-10-13 8:13 ` Avi Kivity
2017-10-14 22:42 ` Dave Chinner
2017-10-15 9:36 ` Avi Kivity
2017-10-15 22:00 ` Dave Chinner
2017-10-16 10:00 ` Avi Kivity
2017-10-16 22:31 ` Dave Chinner
2017-10-18 7:31 ` Christoph Hellwig
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