On Fri, Sep 12, 2008 at 10:34 AM, Karl Pielorz <[EMAIL PROTECTED]>wrote:
> --On 12 September 2008 06:21 -0700 Jeremy Chadwick <[EMAIL PROTECTED]> > wrote: > > As far as I know, there is no such "standard" mechanism in FreeBSD. If >> the drive falls off the bus entirely (e.g. detached), I would hope ZFS >> would notice that. I can imagine it (might) also depend on if the disk >> subsystem you're using is utilising CAM or not (e.g. disks should be daX >> not adX); Scott Long might know if something like this is implemented in >> CAM. I'm fairly certain nothing like this is implemented in ata(4). >> > > For ATA, at the moment - I don't think it'll notice even if a drive > detaches. I think like my system the other day, it'll just keep issuing I/O > commands to the drive, even if it's disappeared (it might get much 'quicker > failures' if the device has 'gone' to the point of FreeBSD just quickly > returning 'fail' for every request). Since I had the opportunity, I tested this recently for both CAM and ATA. Now the RAID engine was gmirror in both cases (my production hardware doesn't do ZFS yet), but I expect the reaction to be somewhat the same. Both systems were Dell 1U's. One, an R200, had SATA disks attached to a plain SATA controller. I believe it may have supported RAID1, but I didn't use that functionality. When a drive was removed from it, it stalled for some time (30 minutes?) and then resumed working. by the time I could type on the machine again, gmirror had decided that the drive was gone and marked the mirror as degraded. The other system was a 1950-III with a SCSI SAS controller attached to an SAS hot-swap backplane. The drives themselves were 750G SATA drives. Yanking one of them resulted in about 5 seconds of disruption followed by gmirror realizing the problem and marking the mirror degraded. Neither system was heavily loaded during the test. _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
