Pathetic SATA performance

["Pete Clarke" <pete@devilincarnate.eclipse.co.uk>]

Hi there,

I have a file server, running Etch, with the following specs:

P4, 1.7Ghz
512MB Ram
2 x SI based SATA I controllers
4 x Maxtor 250GB SATA drives

It is set up with software RAID 5, and the overall performance is terrible.

Every time it reboots (which happens due to dodgy power!), it does a RAID 
resync, this takes up 90% CPU time (for md0_resync process) for 50 hours!!
During this time, ANY access to the drive is painful.

Now, I expected software RAID 5 to be slow, but not this bad - this is the 
reading from hdparm:

bungo:~# hdparm -tT /dev/md0

/dev/md0:
Timing cached reads:     2 MB in  4.71 seconds = 435.05 kB/sec
Timing buffered disk reads:    8 MB in  3.13 seconds =   2.56 MB/sec


Bad eh?

Becuase they're SATA drives, hdparm cannot tune them - or indeed read their 
current settings. Is there any way I can speed this beast up, if not I am 
going to go back to my old PPro200-based file server, running SCSI->FCAL 
bridge.

Cheers,




Pete.