SAS5IR performance issue with Dell 860
韓家標 Bill Hacker
askbill at conducive.net
Sun Nov 25 06:49:01 PST 2007
Espen Tagestad wrote:
> We recently bought 3 new Dell 860 servers with the onboard SAS5/IR SATA
> RAID-controller. They seem to be quite well spec'ed servers with
> management and everything - but I am experiencing av major performance
> issue with the disc i/o. On write I get at max 7-8MB/sec, while read
> gives a bit more (11MB/sec). I tried first with 6.2-RELEASE, and then
> upgraded to 6.3-PRERELEASE without any better results.
> I am aware of some discussion around this issue on these two maillists
> in the spring earlier on this year, but I have not been able to find any
> good resolution. My old firewall/router at home equipped with a 733Mhz
> Pentium 3 processor and a old 40GB IDE harddrive made around year 2001
> performe better. Is there anybody out there with the same problem who
> has solved this issue? Could it be that this is solved in 7.0?
> Thanks in advance.
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.
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