Very interesting. This thread prompted me to test the buffered disk reads
on some of my machines. As expected, my pokey (but trusty) ide drive
system was slower than the scsi ones. But, what really surprised me was
the difference in beformance between my two scsi systems - one brnad new,
and the other not much more than a year old.
"old" scsi setup:
adaptec 2940U2W
2 x 9GB IBM (?deskstar? DDRS-39130D) LVD drives
I'm pretty sure I have the bios set at 80MB/sec (verified w/ /proc/scsi/*)
Timing buffered disk reads: 12.85 MB/sec both disks
new scsi system:
adaptec 29160
1 x 18gb seagate ultra 160 (ST318436LW)
bios set for 160MB/sec tranfers
Timing buffered disk reads: 25.20 MB/sec
The new system is *twice* as fast. buffer-cache reads are more comparable
though (but still better on the new).
Now, it's been a long time since I've mucked with the "old" setup so I
don't remeber if the bios transfer rate can be set above 80 (I don't think
so), but I'm not getting anywhere near 80 anyway.
I had expected the "old" setup to perfrom as well, or even outperform the
nw one. maybe I'm just showing my ignorance here?
Does thsi look right? if not, how can I increase performance on the
"old" setup?
tia
charles
On Thu, 2 Nov 2000, Ronald W. Heiby wrote:
> Thursday, November 02, 2000, 2:21:36 PM, Jamin wrote:
> > As for your performance, you might want to check your HD settings with
> > "/sbin/hdparm". Unless you are using SCSI drives, you most likely don't
> > have the drives running with DMA enabled. This roughly doubled my
> > transfer rates.
>
> Wow, what a great suggestion! I ran the hdparm test on my drive and
> got about 3 Megabytes per second. Then, I turned on DMA for the drive
> and am getting about 11 with the same test! Subjectively, the system
> seems a lot "snappier", too.
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