At 12:48 PM -0500 3/1/2010, iJohn wrote:
On Mon, Mar 1, 2010 at 11:17 AM, Dan <[email protected]> wrote:
FW can throw about 390 Mbps. That's usually faster
than most single devices can sustain.
That's just under 49 MB/s, isn't it? That strikes me as a tad
optimistic given my experience with firewire. Usually it was
somewhere in the 30 to 36 MB/s range (on a good transfer).
The SCSI protocol (recall that FW is actually a form of SCSI-3)
overhead is basically what knocks it down to 390. The rest is lost
between cable length (bit errors that cause packet retrans or crc
repairs), device lags, device buffering pauses, etc.
...by comparison look at USB 2. 480 Mbps raw, but since the main cpu
does most of the work, the throughput gets chopped down to 350 Mb,
before taking into account cable and device issues.
But even assuming that you'd get 49 MB/s I expect that recent hard
drives would have no problem sustaining that rate.
People that run FW400 these days probably didn't pay top dollar for
devices that can keep up with FW800 or even the gb speeds of (e)SATA.
YMMV of course.
- Dan.
--
- Psychoceramic Emeritus; South Jersey, USA, Earth.
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