On Jan 8, 2009, at 4:46 PM, Bron Gondwana wrote: > On Thu, Jan 08, 2009 at 08:01:04AM -0800, Vincent Fox wrote: >> (Summary of filesystem discussion) >> >> You left out ZFS. >> >> Sometimes Linux admins remind me of Windows admins. >> >> I have adminned a half-dozen UNIX variants professionally but >> keep running into admins who only do ONE and for whom every >> problem is solved with "how can I do this with one OS only?" > > We run one zfs machine. I've seen it report issues on a scrub > only to not have them on the second scrub. While it looks shiny > and great, it's also relatively new.
You'd be surprised how unreliable disks and the transport between the disk and host can be. This isn't a ZFS problem, but a statistical certainty as we're pushing a large amount of bits down the wire. You can, with a large enough corpus, have on-disk data corruption, or data corruption that appeared en-flight to the disk, or in the controller, that your standard disk CRCs can't correct for. As we keep pushing the limits, data integrity checking at the filesystem layer -- before the information is presented for your application to consume -- has basically become a requirement. BTW, the reason that the first scrub saw the error, and the second scrub didn't, is that the first scrub fixed it -- that's the job of a ZFS scrub. -rob ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
