[KLUG Members] Re: Ext USB HD compatibility -- yeah, go FireWire (or get devices that do both)

[Bryan J. Smith]

Quoting Tim Gray <tgray@adacplastics.com>:
> I'm in the market for an external USB hard drive that's supported by
> Linux...  Suggestions?

Yeah, go FireWire.

Seriously now, many new drives offer both USB 2.0 and FireWire support in the
same package.  So get one of those.  NOTE:  If you plug it into a USB 1.1
system, don't expect even 1/10th the performance of FireWire.

FYI, you can also buy an enclosure with an ATA-to-USB/FireWire converter for
just over $50 -- so that's another option if you have a spare ATA drive lying
around.

As far as compatibility, I haven't seen a FireWire drive that didn't work with
my Linux box.  At the same time, USB has adopted the SBP standard for storage,
so USB compatibility in Linux for hard drives is almost as good as FireWire.

Unlike FireWire, designed as a high-speed block bus and SCSI peripherial
replacement with a full command set, inter-device communication and
memory-mapped I/O, USB was designed as a low-speed character device bus with no
inter-device communication and no memory mapped I/O**.  USB is devoid of
standards, and most "industry standards" were not only developed after-the-fact,
but largely ignored in all early and even many current products.  E.g., not many
USB modems are ACM-comaptible.

[ **NOTE:  Any memory mapped I/O is on a per-device driver hacked basis, and not
inherit to nor controlled by the bus itself. ]

It has to do with the design of USB.  It was designed to be ultra-simplistic on
the host side, making it easy for Intel and Microsoft.  All the brains goes in
the device driver for the USB device itself.  While standards have helped
improved in many areas, they go often ignored (again, ACM modems).  Storage is
simple though, and it wasn't hard for USB to adopt SBP -- especially when
someone finally realized it was easy to modify those ATA-to-FireWire adapters to
support USB as well.

> 
> -- 
> Tim Gray
> Engineering Sysadmin
> ADAC Plastics, Inc.
> "Trying to compete with Linux is like nailing jello to a tree." - Jeff
> Thomas
> 
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> Members@kalamazoolinux.org
> 
> 



-- 
Bryan J. Smith, E.I. (BSECE)       Contact Info:  http://thebs.org
[ http://thebs.org/files/resume/BryanJonSmith_certifications.pdf ]
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