Date: Fri, 12 Oct 2001 17:53:23 -0700 From: Mike Smith <msmith@freebsd.org> To: David Greenman <dg@root.com> Cc: Alexey Koptsevich <alex@astro.su.se>, scsi@freebsd.org Subject: Re: Adaptec 3210S: RAID5 performance and bus throughput Message-ID: <200110130053.f9D0rNk05668@mass.dis.org> In-Reply-To: Message from David Greenman <dg@root.com> of "Fri, 12 Oct 2001 16:53:18 PDT." <20011012165318.C18001@nexus.root.com>
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> You only need to do two reads, one from the disk you are updating and one > from the disk that has the parity. When you XOR the old data from the parity > data, you've removed it and can XOR in the new data. Two reads, two writes. Blah. I knew my numbers looked wrong, but I was busy trying to make the other point (you don't have to read the stripe) and instead made a fool of myself. Oh well. I only write device drivers anyway. 8) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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