User Name wrote: > Hello relling, > > Thanks for your comments. FWIW, I am building an actual hardware array, so > een though I _may_ put ZFS on top of the hardware arrays 22TB "drive" that > the OS sees (I may not) I am focusing purely on the controller rebuild. > > So, setting aside ZFS for the moment, am I still correct in my intuition that > there is no way a _controller_ needs to touch a disk more times than there > are bits on the entire disk, and that this calculation people are doing is > faulty ? >
I think the calculation is correct, at least for the general case. At FAST this year there was an interesting paper which tried to measure this exposure in a large field sample by using checksum verifications. I like this paper and it validates what we see in the field -- the most common failure mode is unrecoverable read. http://www.usenix.org/event/fast08/tech/ full_papers/bairavasundaram/bairavasundaram.pdf I should also point out that ZFS is already designed to offer some diversity which should help guard against spatially clustered media failures. hmmm... another blog topic in my queue... -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
