SAS5IR performance issue with Dell 860

Chris Marlatt cmarlatt at
Mon Nov 26 07:26:30 PST 2007

韓家標 Bill Hacker wrote:
> You haven't indicated what drives are on that controller, or how (RAID?)
> arranged.,, what sort of on-drive or on-controller cahce and policy.
> Nor how you measured the '..performs better', which a single <anything>
> can often do compared to several of the possible RAID configurations.
> Otherwise, those are not actually 'bad' numbers for sustained I/O -
> especially if anything-at-all is going on at the same time that needs to
> intervene and move the r/w heads 'elsewhere' - however briefly.
> More info?
> Bill

The issue has already been confirmed and a "fix"/hack committed so
there's little point busting his balls for lack of information in his
email. It seems like he was only requesting any updated information on
the issue, not a full diagnosis.

The Dell PE-860 only comes with 2 drives, so its going to be independent
drives, raid 1, or raid 0. Frankly if independent drives or raid 0 are
performing that poorly as well it would seem the issue is even worse
than previously indicated. As for the cache policy, seeing as that's the
fix, your question seems a little odd.

Best regards,


More information about the freebsd-stable mailing list