Very low disk performance Highpoint 1820a

[Eric Anderson]

Steven Hartland wrote:
> I've just finished putting together a new server box spec:
> Dual AMD 244, 2GB ram, 5 * Seagate SATA 400GB on a
> Highpoint 1820a RAID 5 array.
> The machine is currently running 5.4-STABLE ( from the
> weekend ) After install I did some basic tests and the
> disk is return very poor performance low in fact than a
> single disk on a bog standard ATA 100 controller:
> 
> 5.4-STABLE Highpoint 1820a RAID 5 ( 5 disk )
> dd if=/dev/da0 of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 13.348032 secs (49097875 bytes/sec)
> 
> 5.3-RELEASE Highpoint 454 RAID 5 ( 4 disk )
> dd if=/dev/da0 of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 20.410034 secs (32109697 bytes/sec)
> 
> 5.2.1-RELEASE Intel ICH3 UDMA100 ( 1 disk )
> dd if=/dev/ad0 of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 11.142405 secs (58816745 bytes/sec)
> 
> Obviously something is seriously a miss here somewhere as
> both the RAID 5 arrays a producing less throughput than
> a single disk.
> 
> Where do I start looking?

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?

You could make two RAID 5's with the controller, and then stripe those 
in vinum.  You could also do a combo of two stripes in the controller, 
and a vinum mirror in FreeBSD - that would give you decent performance.


Eric




-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
A lost ounce of gold may be found, a lost moment of time never.
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