From: Jeff Garzik <jgarzik@pobox.com>
To: michael@insulin-pumpers.org
Cc: linux-raid@vger.kernel.org
Subject: Re: 3ware escalade vs software raid, from a different jeff
Date: Thu, 19 Feb 2004 23:26:16 -0500 [thread overview]
Message-ID: <40358C68.80205@pobox.com> (raw)
In-Reply-To: <200402191958.i1JJwP225623@bzs.org>
Michael wrote:
> Bear in mind that what you are calling "true hardware raid" is really
> a microprocessor programmed to do the raid algorithims. Usually these
> microprocessors are stretched to the limit to handle the throughput
> of modern udam drives. I don't know but I suspect that the small
> overhead use in the mmu for software raid has far more and faster
> throughput than any of these dedicated microprocessors..... and, you
> can see the code and know it is bug free or will be if you report the
Nod... many hardware RAIDs are turning out this way. A certain vendor
whose name does -not- start with 'A' manages to make their hardware RAID
perform so poorly, it is _half_ the speed of a software RAID using the
same drives, on a single non-RAID Adaptec SCSI controller.
Most hardware RAID isn't 100% ASIC, but rather a general ASIC and
firmware with the RAID code in it.
OTOH, hardware RAID really wins for situations like RAID-1, where you
can -halve- the amount of data going across the PCI bus versus software
RAID.
Jeff
next prev parent reply other threads:[~2004-02-20 4:26 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-18 21:48 3ware escalade vs software raid, from a different jeff Rev. Jeffrey Paul
2004-02-18 22:58 ` Jeff Garzik
2004-02-19 11:49 ` Holger Kiehl
2004-02-19 12:06 ` Joshua Baker-LePain
2004-02-19 17:56 ` Rev. Jeffrey Paul
2004-02-19 19:58 ` Michael
2004-02-19 20:18 ` Ricky Beam
2004-02-19 22:04 ` Scsi adapters and software raid Bob Hillegas
2004-02-20 0:33 ` Kanoa Withington
2004-02-20 4:27 ` Jeff Garzik
2004-02-19 22:33 ` 3ware escalade vs software raid, from a different jeff Scott Long
2004-02-19 23:52 ` Guy
2004-02-19 22:29 ` Scott Long
2004-02-20 4:26 ` Jeff Garzik [this message]
2004-02-20 4:40 ` Scott Long
2004-02-20 0:38 ` Jeff Garzik
2004-02-20 7:19 ` Joshua Baker-LePain
2004-02-19 12:11 ` Måns Rullgård
2004-02-19 12:32 ` Holger Kiehl
2004-02-19 12:32 ` Jeff Garzik
-- strict thread matches above, loose matches on Subject: below --
2004-02-23 22:23 Jeff Gray
2004-02-24 8:06 ` Holger Kiehl
2004-02-24 14:16 ` Joshua Baker-LePain
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