Very low disk performance Highpoint 1820a

[Arne Wörner]

--- Eric Anderson <anderson at centtech.com> wrote:
> First, understand that RAID 5 is dependant on fast hardware to
> performa 
> the XOR operations.  A single disk without any RAID can easily 
> outperform a RAID array if the RAID array is on a 'slow'
> controller. 
> The Highpoint controllers are not exactly high-end fast RAID 
> controllers, so ~50MB/s isn't too bad for that I would say.
> Did you  happen to try a vinum RAID5?  How about a stripe?
> 
Furthermore RAID-5 needs to read the parity block, before it can
update that block, so that there are 2 disc transactions more,
which could explain the better performance of a single disk, too?

Or does the striping effect (inherent to RAID-5) compensate those
2 extra transactions (at least in case of sequential writes)?

-Arne


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