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From: "H. Peter Anvin" <hpa@zytor.com>
To: Bill Davidsen <davidsen@tmr.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
	Neil Brown <neilb@suse.de>, Eyal Lebedinsky <eyal@eyal.emu.id.au>,
	Christian Pernegger <pernegger@gmail.com>,
	linux-raid@vger.kernel.org
Subject: Re: mismatch_cnt questions
Date: Thu, 08 Mar 2007 20:20:36 -0800	[thread overview]
Message-ID: <45F0E094.4060809@zytor.com> (raw)
In-Reply-To: <45F0BFBA.5010201@tmr.com>

Bill Davidsen wrote:
> 
> When last I looked at Hamming code, and that would be 1989 or 1990, I 
> believe that I learned that the number of Hamming bits needed to cover N 
> data bits was 1+log2(N), which for 512 bytes would be 1+12, and fit into 
> a 16 bit field nicely. I don't know that I would go that way, fix any 
> one bit error, detect any two bit error, rather than a CRC which gives 
> me only one chance in 64k of an undetected data error, but I find it 
> interesting.
> 

A Hamming code across the bytes of a sector is pretty darn pointless, 
since that's not a typical failure pattern.

	-hpa

  reply	other threads:[~2007-03-09  4:20 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-04 11:22 mismatch_cnt questions Christian Pernegger
2007-03-04 11:50 ` Neil Brown
2007-03-04 12:01   ` Christian Pernegger
2007-03-04 22:19     ` Neil Brown
2007-03-06 10:04       ` mismatch_cnt questions - how about raid10? Peter Rabbitson
2007-03-06 10:20         ` Neil Brown
2007-03-06 10:56           ` Peter Rabbitson
2007-03-06 10:59             ` Justin Piszcz
2007-03-12  5:35             ` Neil Brown
2007-03-12 14:26               ` Peter Rabbitson
2007-03-04 21:21   ` mismatch_cnt questions Eyal Lebedinsky
2007-03-04 22:30     ` Neil Brown
2007-03-05  7:45       ` Eyal Lebedinsky
2007-03-05 14:56         ` detecting/correcting _slightly_ flaky disks Michael Stumpf
2007-03-05 15:09           ` Justin Piszcz
2007-03-05 17:01             ` Michael Stumpf
2007-03-05 17:11               ` Justin Piszcz
2007-03-07  0:14               ` Bill Davidsen
2007-03-07  1:37                 ` Michael Stumpf
2007-03-07 13:57                   ` berk walker
2007-03-07 15:01                   ` Bill Davidsen
2007-03-05 23:40         ` mismatch_cnt questions Neil Brown
2007-03-07  0:22           ` Bill Davidsen
2007-03-08  6:39           ` H. Peter Anvin
2007-03-08 13:54             ` Martin K. Petersen
2007-03-09  2:00               ` Bill Davidsen
2007-03-09  4:20                 ` H. Peter Anvin [this message]
2007-03-09  5:20                   ` Bill Davidsen
2007-03-08  6:34         ` H. Peter Anvin
2007-03-08  7:00           ` H. Peter Anvin
2007-03-08  8:21             ` H. Peter Anvin
2007-03-13  9:58               ` Andre Noll
2007-03-13 23:46                 ` H. Peter Anvin
2007-03-06  6:27       ` Paul Davidson
2008-05-12 11:16   ` Bas van Schaik
2008-05-12 14:31     ` Justin Piszcz

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