From: Mark Lord <lkml@rtr.ca>
To: "J.A. Magallon" <jamagallon@able.es>
Cc: Lista Linux-Kernel <linux-kernel@vger.kernel.org>,
Jeff Garzik <jgarzik@pobox.com>
Subject: Re: md RAID over SATA performance
Date: Fri, 03 Sep 2004 12:33:30 -0400 [thread overview]
Message-ID: <41389CDA.5060609@rtr.ca> (raw)
In-Reply-To: <1094169937l.17931l.0l@werewolf.able.es>
Even with hardware RAID the numbers I see are not often
much better than this.
Unless O_DIRECT is used (hdparm --direct), in which case they
immediately jump to a level that is more limited by the PCI
and memory speeds of the system.
Eg. 205Mbytes/sec for a 4-drive RAID0 over 64-bit/66Mhz PCI.
I guess the page_cache overhead is rather substantial
for the simple read-a-sequential-block test.
Cheers
--
Mark Lord
(hdparm keeper & the original "Linux IDE Guy")
next prev parent reply other threads:[~2004-09-03 16:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-03 0:05 md RAID over SATA performance J.A. Magallon
2004-09-03 0:47 ` J.A. Magallon
2004-09-03 8:09 ` David Greaves
2004-09-03 16:15 ` Mark Lord
2004-09-03 11:13 ` Alan Cox
2004-09-03 13:24 ` Brad Campbell
2004-09-03 16:33 ` Mark Lord [this message]
2004-09-03 20:27 ` Tomasz Torcz
2004-09-04 13:38 ` Mark Lord
2004-09-03 21:58 ` J.A. Magallon
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