Re: Very low disk performance Highpoint 1820a

----- Original Message ----- 
From: "Brian Candler" <B.Candler_at_pobox.com>

> - try reconfiguring your array as 5 separate disks, and dd from a single
> disk. If it's still slower than your ATA disk, then it's probably SCSI
> transfers or controller I/O bandwidth which are slowing things down.

Was gonna try pulling one of the disks and seeing what the indiviual disk
performance was but considering  3 other controllers from different
manufacturers are all showing the same on 5.x but not on 4.x ( from one
report ) It suggests something more sinister in 5.x

> If you get equal or better performance than your ATA disk, then it becomes
> likely that the RAID configuration is the bottleneck.

Inlikely considering it has 8 SATA 150 channels on 64bit PCI-X _at_ 133Mhz

> - try reconfiguring your array as two mirrored pairs, and do the same test
> again.

> RAID5 isn't necessarily a good choice for high-performance applications; a
> single block write requires two reads and two writes (to the target data
> disk and the parity disk), and therefore write access to the array is likely
> to be *slower* than to a single disk. You might be better off with
> mirroring. It handles random writes better, and you may get double the
> random read performance since there are two copies of all the data.

Primarly interested in read and considering write performance us 140MB/s
compared with 40MB/s read not really worried about that atm
 
> RAID5 is acceptable if your application is mostly read-only though (which
> your dd test is, of course)

Thanks for the ideas though :)

    Steve


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