IEEE 1394

[Donald Becker]

On Thu, 5 Dec 2002, Eugen Leitl wrote:

> After I've posted a link to the Oracle library for clustering over 1394 
> a while back Apple mumbled something about RFC 2734 (IP over 1394):
> 
> 	http://developer.apple.com/firewire/IP_over_FireWire.html
> 
>  All Apple computers sold today include one or more FireWire ports. 
>  Because FireWire can transfer data at up to 400 megabits/second, it is 
>  suitable for networking and clustering solutions, as well as temporary 
>  connections to the internet using Internet Sharing.

By "clustering" they mean fail-over.
  "N-way clustering, where N<=2".

If you want scalable performance and matrix availability, you will need
an IEEE1394 switch.  Pretty much every vendor with an 10Gb Ethernet
switch also makes IEEE1394 switches ;->  (N=0)

> Since I've never seen real numbers for IEEE 1394 latency I did some 
> websearches, and finally found some meat:

We never see them because (!!!)

> "The IEEE 1394 bus has a minimum latency of a few hundred microseconds and 
> a worst-case delay of a few milliseconds.

I think that they are very optimistic with that worst-case delay.

> For large data blocks, this bus 
> uses direct memory access (DMA) similar to PCI bus mastering that reduces 
> the influence of software protocol overhead on the transfer rate.

This is great for fixed-sized repeated frames such as video or
contiguous disk block reads, but adds additional overhead for other
communication.  And most cluster communication is "other".

-- 
Donald Becker				becker at scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993