Hi. On Thu 2003-01-30 at 21:47:11 +1100, [EMAIL PROTECTED] wrote: [...] > raid, I would get results around > 387mb cache, and 45mb read. The settings I would use on > these systems would be hdparm -X68 -c3 -d1 -u1 -m16. > Now, when I ran hdparm in md9 (had to install, the distro > didn't have it included) with the s/raid, I get results around > 330mb cache, and 5.5mb read. BIG performance drop.
Sounds as if DMA is disabled.
> When trying to set any parameter setting through hdparm,
> it tells me that it can not use these setting on a scsi device.
I think, using the command on the underlying devices (/dev/hda? etc.)
should work. The /dev/md0 is only a logical device.
Btw, note, that hdparm only measures raw throughput whereas the speed
advantage of RAID also comes from improving access times (i.e.
lowering latency). In other words: The RAID-level with highest hdparm
rating is not necessarily the one which is fastest for real
applications.
Regards,
Benjamin.
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