Date: Thu, 28 Apr 2005 09:42:16 -0500 From: Eric Anderson <anderson@centtech.com> To: Steven Hartland <killing@multiplay.co.uk> Cc: freebsd-performance@freebsd.org Subject: Re: Very low disk performance Highpoint 1820a Message-ID: <4270F648.5030501@centtech.com> In-Reply-To: <069901c54bfd$2967ba40$7f06000a@int.mediasurface.com> References: <069901c54bfd$2967ba40$7f06000a@int.mediasurface.com>
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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 -- ------------------------------------------------------------------------ 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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