Yes, I was going to say this too, make sure the SATA settings in the
BIOS are all set to SATA operation and not "legacy", then you should
see /dev/sda and /dev/sdb and all DMA, IO size, NCQ and multiple
sector
settings will be properly negotiated at start-up.
I bit the bullet and rebooted my system. I couldn't find anything in
the BIOS regarding this. However, while the system was down, I
simply swapped the SATA connections of one of the optical drives with
the slow hard disk. Upon reboot, the slow disk formerly at /dev/hda
disk was now /dev/sda (and the former /dev/sda was now /dev/sdb) and
the two optical drives are /dev/hda and /dev/hdb. Moreover, the disk
drive now performs as before.
So why does a simple swap like this cause such a performance
difference (almost an order of magnitude!)?
To set these via hdarpm:
hdparm -c 1 /dev/hda (for 32-bit)
hdparm -d 1 /dev/hda (for DMA)
hdparm -m 16 /dev/hda (multiple sector IO = 16 sectors)
These can be combined to: hdparm -c 1 -d 1 -m 16 /dev/hda
Now that the drive is /dev/sda, hdparm doesn't work. Is there a
similar utility to change these settings on SATA drives that show up
as /dev/sdx? Is this even needed? In my case, I'm happy to get back
the previous performance, but if there is a way to increase it even
further, I'd like to know.
Alfred
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
