[GRLUG] External drive transfer rates

[Bob Kline]

Both the internal drive and the
one hanging off the USB 2 cable
are IDE.

When I run the backup,  the
machine is doing little else, so I'd
guess the CPU is not particularly
loaded.

I'm a little puzzled as to why the
hdparm  "d" parameter does not
function,  but  the write says hdparm
does not work with all chip sets.

Well,  for now the backups work.
I just have to wait.  The transfer
rate is the 8 Mbps I mentioned.  Yet
on another USB 2 port I can move
data between two machines over
a wireless link at 45 to 50 Mbps.

So I think there is a mystery here
yet.   I'd like to see at least that when
backing up to an external drive on
a USB 2 port.

Someday...

    -Bob


> > hdparm -cuda  /dev/x
> >
>
> I  forgot about one thing Bob.
> hdparm only works for IDE drives, since your drive is interfaced via USB
> it must be /dev/s-something right?
>
> if that it the case than DMA shouldn't be needed at all.
>
> As the purpose of DMA is to free up the processor maybe you should watch
> the Load Avg when copying a file to see if it's
> abnormally high.
>
>
> only reports for a:  "readahead =  256 (on)
> >
> > Running   "hdparm -d1 /dev/x"
> > result in "HDIO_SET_DEM failed: Invalid argument."
> >
> > The hdparm man page suggest that
> > in rare cases one has to use the -X
> > parameter.  It also says this can cause
> > real headaches.
> >
> >     -Bob
> >
> >
> >
> >
>
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