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Re: XFS buffered sequential read performance low after kernel upgrade

To: xfs@xxxxxxxxxxx
Subject: Re: XFS buffered sequential read performance low after kernel upgrade
From: Robert Brockway <robert@xxxxxxxxxxxxxxxxx>
Date: Sat, 13 Mar 2010 10:24:02 -0500 (EST)
In-reply-to: <20100313001626.GE4732@dastard>
References: <4B9A2A00.1050304@xxxxxxxxxxxxxxxxx> <20100313001626.GE4732@dastard>
User-agent: Alpine 1.10 (DEB 962 2008-03-14)
On Sat, 13 Mar 2010, Dave Chinner wrote:

Also, the XFS partitions are on the inner edge of the disk, so they
are always going to be slower (can be as low as half the speed) than
partitions on the outer edge of the disk for sequential access...

Hi Dave. Hasn't it been the case for a long time that the sectors on the HDD are no long necessarily numbered from the outside in? I understood some HDD are numbered in the opposite direction and some are striped and that HDD manufacturers tend not to release this info. Short of timing tests I believe there is no easy easy way to figure out the sequence anymore.

This has tended to nullify the old wisdom of putting the root filesystem at the beginning of the disk[1].

[1] Which was done in the past because it was faster.

Cheers,

Rob

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