On Tue, Jan 24, 2012 at 10:50 AM, Stefan Ring <stefan...@gmail.com> wrote:

> After having read this mailing list for a little while, I get the
> impression that there are at least some people who regularly
> experience on-disk corruption that ZFS should be able to report and
> handle. I’ve been running a raidz1 on three 1TB consumer disks for
> approx. 2 years now (about 90% full), and I scrub the pool every 3-4
> weeks and have never had a single error. From the oft-quoted 10^14
> error rate that consumer disks are rated at, I should have seen an
> error by now -- the scrubbing process is not the only activity on the
> disks, after all, and the data transfer volume from that alone clocks
> in at almost exactly 10^14 by now.

    The 10^-14 (or 10^-15 or 10^-16) number is a statistical average.
So if you have a big enough pool of drives, for every drive that moves
more than 10^14 with no uncorrectable errors, then there will be a
drive that moves less than 10^14 before hitting an uncorrectable
error. The three 1 TB consumer drives you have must have been
manufactured on a "good day" and not a "bad day" :-)

    Note the error rate is 10^-14 (or 10^-15 or 10^-15) which
translates into one error per 10^14 bits (bytes ?) transferred to /
from the drive. Note the sign change on the exponent :-)

Paul Kraus
-> Senior Systems Architect, Garnet River ( http://www.garnetriver.com/ )
-> Sound Coordinator, Schenectady Light Opera Company (
http://www.sloctheater.org/ )
-> Technical Advisor, Troy Civic Theatre Company
-> Technical Advisor, RPI Players
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