From mboxrd@z Thu Jan  1 00:00:00 1970
From: jkunz@unixag-kl.fh-kl.de (Jochen Kunz)
Date: Fri, 22 Jan 2010 10:14:24 +0100
Subject: [TUHS] Irwin 285
In-Reply-To: <20100121204429.GH9956@bitmover.com>
References: <48239d391001210407t7633e9d1p692be7de51ccb9dd@mail.gmail.com>
	<20100121181147.97ae525c.jkunz@unixag-kl.fh-kl.de>
	<20100121185917.GA25619@freebie.xs4all.nl>
	<20100121204829.672d59a7.jkunz@unixag-kl.fh-kl.de>
	<20100121195619.GE25687@freebie.xs4all.nl>
	<20100121195818.GF9956@bitmover.com>
	<20100121200034.GG25687@freebie.xs4all.nl>
	<20100121201125.GG9956@bitmover.com>
	<46b366131001211226v1a133901mefa41b3258a5b173@mail.gmail.com>
	<20100121204157.GI25687@freebie.xs4all.nl>
	<20100121204429.GH9956@bitmover.com>
Message-ID: <20100122101424.50c0e716.jkunz@unixag-kl.fh-kl.de>

On Thu, 21 Jan 2010 12:44:29 -0800
Larry McVoy <lm at bitmover.com> wrote:

> Disks are much higher volume and are forced to be reliable "enough".
That "enough" is the critical point. Check the average read failure
rate of SATA drives. It is 1 per 10^14 bits for my ST3500320AS. The
drive has a capacity of 512 bytes/sect x 976773168 sectors. I.e. I will
get at least one read error when I try to read the entire disk 25
times. If I build a RAID out of 5 of this drives I only need 5 reads
through the RAID to get a read error and the RAID will degrate.

> If you aren't backing up with a crc then you are doing it wrong.
With a CRC you can detect bit rott. (Probably. Somthing like MD5 or
SHA-1 is mch better then a CRC.) But you can't repair the defect data.
So you want ECC...
-- 


tschüß,
       Jochen

Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/

_______________________________________________
TUHS mailing list
TUHS at minnie.tuhs.org
https://minnie.tuhs.org/mailman/listinfo/tuhs