very poor performance of LSILogic's SATA 150-6D (RAID5)

[Oliver Lehmann]

Mikhail Teterin wrote:

> Hello!
> 
> We are observing very low performance of the 5- and 6-drive RAID5 array on the 
> LSILogic.
> 
> For formal comparision we created two logical drives -- a 5-drive RAID5 and a 
> 1-drive RAID0. (All 6 disks are identical 200Gb Western Digital).
> 
> According to iozone, the 5-drive RAID5 gets from 3 to 8 Mb/s. The 1-drive 
> RAID0 goes from 20 to 50Mb/s.
> 
> Now, the controller has no battery and thus is not allowed to cache much, but 
> is the difference really supposed to be so great? It has 5 disks at its 
> disposal, after all...

Hi,

before i purchased my 3ware 9500S-4LP I tried an LSI 4port too and I
experienced same bad results (which lead me to change it to 3ware). I was
running it with 4 WD25000KS.

a single disk:
6553600000 bytes transferred in 225.704693 secs (29036171 bytes/sec) (UP)
RAID-0:
6553600000 bytes transferred in 204.397157 secs (32063068 bytes/sec) (UP)
RAID-5
4194304000 bytes transferred in 146.751626 secs (28580971 bytes/sec) (UP)

Notice that all results where takes with an uni-processor (UP) config
even my system is SMP. Running the LSI wit SMP was _much_ slower
(10MB/sec for RAID-5 iirc).

-- 
 Oliver Lehmann
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