8.0-RELEASE: disk IO temporarily hangs up (ZFS or ATA related problem)

Alexander Motin mav at FreeBSD.org
Fri Dec 18 12:01:11 UTC 2009

Alexander Zagrebin wrote:
> May be a problem is in ata? WD15EADS is a "green" series of drives.

If you don't receive TIMEOUT messages, then commands probably complete
successfully. Loads above 100% may mean that requests are running for
few seconds. It shouldn't happen normally.

Have you tried to check whole drive surface? Have you checked SMART
reports? I had a drive onece, which had so many media problems and
relocated sectors, that I was unable to burn CD from it, so slow it was.
Same time there was no bad sectors on that drive, reported to OS, drive
handled everything. It was just extremely slow.

Have you tried to rewrite _while_ drive media with dd? Some media errors
could only be resolved only during write operation.

> Is there a method to completely reset sata channel and drive?
> atacontrol reinit will do it?


Alexander Motin

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