On 17.04.2010 00:34, Frank Middleton wrote: > On 04/15/10 12:19 AM, James C.McPherson wrote: > >> From what I've observed, the consistent feature of this >> problem (where no SAS expanders are involved) is the >> use of WD disk drives. > > If I run Open Solaris (and ZFS) on a COMSTAR initiator, run a > scrub, and also run a scrub on the ZFS target, the iops get > cranked up to a sustained 130 or so and eventually something > very similar to CR6894775 may occur. Setting /etc/system > zfs:zfs_vdev_max_pending = 4 definitely reduces the frequency > of it happening but eventually it does if you do it often enough. > > This on a simple whole-disk mirror of Seagate 7200 RPM drives > on SPARC running SXCE snv125 with 4GB. Both disks are on the > same controller with no expanders. So if this is the same problem > (and I'm pretty certain it is) then it happens on (these) Seagates, > too. > > It seems to require a power cycle to reset; if you can get it to > do a warm reboot (e.g., by forcing a panic) the disks remain offline. > What is the difference between a warm reboot and a power cycle > in this context? Just wondering if there is some way that the mpt > driver could detect that every disk on a given controller has suddenly > gone offline more or less at once, then it could somehow reset the > controller. Sorry if this is a naive question, but when this happens, > however rarely, it is rather annoying albeit relatively harmless, and a > brute force fix would be better than having to power cycle, which > is always scary...
Since I was seeing similar behavior with just a tape autoloader behind
the MPT (when a queue builds up, controller ends up in a bus-reset-loop
as seen from the devices), could this be timing-related? Could it be as
simple as the MPT driver needing a larger value for timeouts before it
starts bus-resetting?
//Svein
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