From: Michael Monnerie <michael.monnerie@is.it-management.at>
To: xfs@oss.sgi.com
Cc: Stan Hoeppner <stan@hardwarefreak.com>,
John Bokma <contact@johnbokma.com>
Subject: Re: 30 TB RAID6 + XFS slow write performance
Date: Sun, 24 Jul 2011 10:47:14 +0200 [thread overview]
Message-ID: <201107241047.19745@zmi.at> (raw)
In-Reply-To: <4E2BB859.1050200@hardwarefreak.com>
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On Sonntag, 24. Juli 2011 Stan Hoeppner wrote:
> Is the NetApp FC/iSCSI attachment performance still competitive for
> large file/streaming IO, given that one can't optimize XFS stripe
> alignment, and with no indication of where the file fragments are
> actually written on the media? Or does it lag behind something like
> a roughly equivalent class Infinite Storage array, or IBM DS?
I can't tell about performance difference. But I'd like to explain two
fundamental differences to all other storages:
1) WAFL *never* overwrites an existing block. Whenver there's a write to
an existing block, that block is instead written to a new location,
afterwards the old block mapped to the new one. This is a key factor to
keeping performance up when using snapshots and deduplication.
2) WAFL never does small or random writes. All writes are collected in
NVRAM, and then written as one large sequential write, always one full
stripe is written.
That means for workloads with lots of small random writes, NetApp
storages beat the hell out of the disks, compared to other storages.
I can't tell for large seq. writes, though, I don't have such workload.
--
mit freundlichen Grüssen,
Michael Monnerie, Ing. BSc
it-management Internet Services: Protéger
http://proteger.at [gesprochen: Prot-e-schee]
Tel: +43 660 / 415 6531
// Haus zu verkaufen: http://zmi.at/langegg/
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prev parent reply other threads:[~2011-07-24 8:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-18 19:58 30 TB RAID6 + XFS slow write performance John Bokma
2011-07-19 0:00 ` Eric Sandeen
2011-07-19 8:37 ` Emmanuel Florac
2011-07-19 22:37 ` Stan Hoeppner
2011-07-20 0:20 ` Dave Chinner
2011-07-20 5:16 ` Stan Hoeppner
2011-07-20 6:44 ` Dave Chinner
2011-07-20 12:10 ` Stan Hoeppner
2011-07-20 14:04 ` Michael Monnerie
2011-07-20 23:01 ` Dave Chinner
2011-07-21 6:19 ` Michael Monnerie
2011-07-21 6:48 ` Dave Chinner
2011-07-22 6:10 ` Michael Monnerie
2011-07-22 18:05 ` Stan Hoeppner
2011-07-22 23:10 ` Dave Chinner
2011-07-24 6:14 ` Stan Hoeppner
2011-07-24 8:47 ` Michael Monnerie [this message]
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