Hi, all, Am 09.01.2011 um 11:03 schrieb Matthew Seaman:
> [*] All of this mathematics is pretty suspect, because if two drives > fail simultaneously in a machine, the chances are the failures are not > independent, but due to some external cause [eg. like the case fan > breaking and the box toasting itself.] In which case, the comparative > chance of whatever it is affecting three or four drives at once renders > the whole argument pointless. I assume you are familiar with these papers? http://queue.acm.org/detail.cfm?id=1317403 http://queue.acm.org/detail.cfm?id=1670144 Short version: as hard disk sizes increase to 2 TB and beyond while the URE rate stays in the order of 1 to 10^14 blocks read, the probability of encountering an URE during rebuild of a single parity RAID approaches 1. Best regards, Patrick -- punkt.de GmbH * Kaiserallee 13a * 76133 Karlsruhe Tel. 0721 9109 0 * Fax 0721 9109 100 i...@punkt.de http://www.punkt.de Gf: Jürgen Egeling AG Mannheim 108285 _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
