Re: another question (was Re: patent question)

[Stephen Bailey <steph@cs.uchicago.edu>]

> > i have another quick question. for a local area application, 
> > why hasn't anyone done scsi over ethernet? (ie encapsulating 
> > scsi commands into the ethernet package). why use a higher 
> > level protocol and work with all the latency and overhead problem?
> 
> Check the list archives for info on an Adaptec demo of this, and I'm
> sure Paul von Stamwitz can provide additional information (off the
> list, please).  Encapsulating directly on Ethernet runs into scaling
> problems - the first time one needs to get off the LAN or VLAN that
> the traffic started on, one discovers that an IP header is an immensely
> useful thing to have.

I can add that SCSI on ST (SST) is another implemented form of SCSI on
Ethernet with existing, hardware accelerated implementations.  See
www.genroco.com for more information.

What David says is correct.  You CAN build SANs this way, but you must
careful control the configuration, which is another reason why
scalability is limited.  In some cases, having an Ethernet SAN which
requires this careful configuration control is still better than
needing two network attachment infrastructures (Ethernet & FCP).

Steph