Some External HDD Questions

[Matt Graham]

From: Jorge Delacruz <alterthegrid at yahoo.com>
> Matt Graham <danceswithcrows at usa.net> wrote:
> > 2M/s?  That doesn't sound right for either USB1 or USB2.
> I plugged in a USB drive and [dd'ed] the internal drive to
> a file on the external USB drive.  It took 9 hours to dd a 
> 40 GB internal drive, so 1.2 MB/sec

What did you specify for bs= ?  32k or 64k would have probably
worked the best.  If you don't specify a bs= , dd reads and
writes 512-byte blocks.  This is ... suboptimal, as 64 reads of
0.5K take much longer than 1 read of 32K.

> I used USB2 hardware. Maybe this is a limitation with dd? 
> The external hard drive's light blinks a lot and the box 
> seems I/O bound when I do it.

Of course it's going to be I/O bound; you're doing a whole
bunch of I/O.  See above for a possible explanation.  Also,
dd is the stupidest backup method in existence as it copies 
everything including blocks that aren't in use.  Use partimage
or tar or rsync; that's what they're there for.