Re: iSCSI: Send Targets and Report Portal Groups

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

Joe,

> Initiators that only need to discover a single target name/address are not
> helped much by SendTargets.

They are if they don't already know the target's name, and there is
not a default operational target.

I do think that single target end points are going to be a common
case.  The question is whether you require the initiator to know the
network address (probably just IP address or name) AND the target
name, or just the network address.

If you have a default operational target, OR if you provide
SendTargets, you only need to know the network address.  Otherwise,
you need to know the target name too.  Personally, I think that
requiring that an initiator know both the address and the target name
(OR requiring an N/D service) is a mistake.  It means an administrator
must be able to find each target's address through a side channel.  If
the target is racked into a large system, you probably won't be able
to read it off the box itself, and it may not have an appropriate
console or other facility from which to interrogate the target.

I'll renew my claim that to get started in iSCSI, it shouldn't be
necessary to have additional `enterprise-class' resources (i.e. a
complete N/D service).  It should be easy to stage a SMALL
configuration by just:
  1) configuring the initiator to be a network citizen
  2) configuring the target(s) to be a network citizen
  3) pointing the initiator at the target
This is analogous to what PL_DA offered for FC.  Certainly, much of
the sizzle of FC is in the larger network case, but first people put
together PL_DA configurations (and products), before deciding it was
time to try something bigger.

In other words, we need either SendTargets OR a default operational
target (and I say why not both?) to support this simple case.  We
shouldn't throw BOTH of these out.

Steph