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From: Alex Tomas <alex@clusterfs.com>
To: Eric <erpo41@gmail.com>
Cc: linux-ext4 <linux-ext4@vger.kernel.org>
Subject: Re: [RFC] store RAID stride in superblock
Date: Sat, 12 May 2007 13:38:01 +0400	[thread overview]
Message-ID: <46458AF9.404@clusterfs.com> (raw)
In-Reply-To: <1178962364.20145.99.camel@eric-laptop>

I don't quite follow? how would you "probe" ? for example,
there is DDN array which write well with 1MB aligned/sized
requests only. thus, mballoc tries to align allocation
requests WRT to this constrain. do you mean incorporation
storage benchmark in the mount procedure?

thanks, Alex

Eric wrote:
> That hadn't occurred to me. Perhaps the filesystem driver or mkfs could
> probe for the stride in those cases? If the code asks for, say, 10MiB of
> data from the block device and it gets back sectors that are spaced
> 128KiB apart before it gets the rest of the data, it can make an
> intelligent guess about the stride.
> 
> I wonder what penalties would come from a bad guess due to a cache in
> between the block device driver and the disk platters, or other load on
> a SAN...
> 
> 
> Eric
> 

  reply	other threads:[~2007-05-12  9:38 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-12  2:02 [RFC] store RAID stride in superblock Andreas Dilger
2007-05-12  2:21 ` Eric Sandeen
2007-05-12  8:11 ` Eric
2007-05-12  8:33   ` Alex Tomas
2007-05-12  9:32     ` Eric
2007-05-12  9:38       ` Alex Tomas [this message]
2007-05-12 16:14         ` Eric
2007-05-12 15:26   ` Andreas Dilger
2007-05-19  2:08 ` Theodore Tso
2007-05-24 11:44 ` Andreas Dilger
2007-05-24 14:15   ` Rupesh Thakare
2007-05-31 16:21     ` Theodore Tso
2007-05-31 20:19       ` Andreas Dilger
2007-05-31 21:02         ` Kalpak Shah
2007-05-31 21:33         ` Theodore Tso
2007-05-31 22:01           ` Eric Sandeen
2007-05-31 22:03           ` Andreas Dilger

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