Date: Wed, 14 Jan 2004 14:53:50 +0200 From: Ari Suutari <ari@suutari.iki.fi> To: freebsd-stable@freebsd.org Subject: Adaptect raid performance with FreeBSD Message-ID: <200401141453.50150.ari@suutari.iki.fi>
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Hi, I have been wondering if my disk setup should perform better than it is now doing. I have a dual PIII 500 Mhz with intel server mother board. (a couple of years old). On that, I have DPT (or currently Adaptec) raid controller "DPT PM2654U2", which supports 40 Mhz SCSI bus, giving a theoretical data transfer speed of 80 MB/s. There are two physical disks, which have been mirrored (ie. raid-1). The disks are maxtor atlas 10K4, I think that maxtor tells that they should give sustained transfer rate up to 72MB/s. I have confirmed that SCSI bus is at 80MB/s speed with dptutil. The system is running FreeBSD 4.8. However, when reading raw device with dd like this: dd if=/dev/rda1s1a of=/dev/null bs=1m count=100 100+0 records in 100+0 records out 104857600 bytes transferred in 4.193832 secs (25002814 bytes/sec) So, I get only about 25MB/s. Shouldn't I be getting something like 70 MB/s, or even more since there are two disks that can server read requests ? Maybe there is something I could tune ? The BIOS doesn't have much, there is only setting to enable bus mastering (enabled) and another for pci latency timer values (was 40, I think) Ari S. -- Ari Suutari Lemi, Finland
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