Date: Sun, 15 Jun 2008 16:46:37 -0400 (EDT) From: vogelke+software@pobox.com (Karl Vogel) To: freebsd-questions@freebsd.org Subject: Re: FreeBSD + ZFS on a production server? Message-ID: <20080615204637.C991BB7BA@kev.msw.wpafb.af.mil> In-Reply-To: <20080609232736.X39884@wojtek.tensor.gdynia.pl> (message from Wojciech Puchar on Mon, 9 Jun 2008 23:31:35 %2B0200 (CEST))
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>> On Mon, 9 Jun 2008 23:31:35 +0200 (CEST), >> Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> said: W> but why you need [a filesystem for linux that do checksum on the fly]?! all W> PATA/SATA drives do checksumming on every read. in hardware, no CPU load. These days, hardware isn't just hardware. A disk drive can have around 300,000 lines of low-level firmware, and who wants to bet that it's completely bug-free? Silent-write errors are actually a big problem: http://www.usenix.org/publications/login/2008-06/openpdfs/bairavasundaram.pdf An Analysis of Data Corruption in the Storage Stack "In this paper, we present the first large-scale study of data corruption. We analyze corruption instances recorded in production storage systems containing a total of 1.53 million disk drives, over a period of 41 months. We study three classes of corruption: checksum mismatches, identity discrepancies, and parity inconsistencies. We focus on checksum mismatches since they occur the most; more than 400,000 instances of checksum mismatches over the 41-month period." -- Karl Vogel I don't speak for the USAF or my company Mangled song lyric: Looks like tomatoes Actual lyric: Looks like we made it. (Barry Mannilow)
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