ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks

Patrick M. Hausen hausen at punkt.de
Sun Jan 9 10:32:34 UTC 2011

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?


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.

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