Re: Awful hard drive performance

On Thu, 31 Jul 2008 16:02:08 +0000, stan wrote:

James H. Newman <NewJames@xxxxxxxxxxx> wrote:

The problem is, when I try to enable DMA on these drives by
means
of hdparm -d, using_dma remains off. Anybody can offer an explanation
as to why? I understand this must be turned on in order to have decent
disk performance. In fact, I noticed that when transferring big files
from this box to other boxes in my LAN via SCP, instead of attaining
the roughly 8-10 MBs expected, the transfer rate never goes above 2.3
MBs. I wonder if this is the reason why?

Well- since you are measuring a whole bunch more than disk access speed,
you first need to find out where the bottleneck is.

I'd suggest starting by looking at transfer speed from one of your disks
to another ON THE SAME COMPUTER. If that's nice and fast then clearly
your issue above is network related and not disk access related.

The transfer speed is the same meager 2 MBs when I SCP a file to
another file in the same computer.

What leads you to expect 8-10MB/s for this transfer?

That's what I get when I transfer data (with SCP) between any
other two machines in my LAN. In fact, it is more like 11 MBs.

.