[Gllug] USB Discs

[Andy Farnsworth]

Whoops, I don't know where you got your numbers, but lets work them through.

USB - 12 Mb/s =~ 1.5 MB/s
USB 2.0 - 480 Mb/s =~ 60 MB/s
Firewire - 400 Mb/s =~ 50 MB/s

While these throughput speeds are maximums, hard drive sustained transfer
speeds are much less.  As long as you are reading from the Hard Drive's
cache you will reach these speeds.  A decent IDE drive will get 35 MB/s
(about 20x faster than USB 1.1) while a laptop drive will get less than
that.  Granted, I would rather use USB 2.0 or Firewire instead of 12 Mb USB
and I wouldn't plan on using a USB drive as a main storage drive, but it
does make moving it from one computer to another very easy.

Andy Farnsworth

-----Original Message-----
From: gllug-admin at linux.co.uk [mailto:gllug-admin at linux.co.uk]On Behalf
Of Tethys
Sent: November 05 2002 17:31
To: gllug at linux.co.uk
Subject: Re: [Gllug] USB Discs



"t.clarke" writes:

>Don't know what the performance of Hard Discs over USB is like

Poor. USB is IIRC 12Mb/s, i.e., well over 100 times slower than a
typical SCSI or IDE disk. Firewire drives, while still slow compared
to "Real" disks, are at least much better at 400Mb/s -- comparable
to internal hard disks of a few years ago.

Tet

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