Re: SCSI URL scheme

[Raghavendra Rao <jpr@divyaroot.India.Sun.COM>]

> 
> First off, this is suppose to be done (normally) once, but perhaps at
> various (logical) Plug & Play  points.  If we are talking about the Plug &
> Play points in time, then there could be some additional conversation.  But
> independent of that, which so far I think we have been, the Host determines
> ALL his addressable LUs when he comes up, and today that means "REPORT
> LUNS", followed by approprate INQUIRYs.  This is not a big deal at bring
> up.
> 

It depends on the storage controller and the configuration. If iSCSI indeed
becomes very popular, it is not hard to visualize a lot of compute nodes
(of the order of 100s just to start with) accessing/sharing a big storage
device that could have a lot of LUs (of the order of thousands at the least).

It is possible to configure the storage device to selectively report LUs
in the REPORT LUN response so as to limit the number of INQUIRYs fired from
the initiators - But I see this only as a work around - not a solution
to the problem.

I think a better way to translate a LU-WWN to LUN value is required to avoid
overwhelming number of INQUIRYs fired from all the compute nodes trying
to access the storage device; This is not only wasting the network bandwidth,
but is also slowing down the host's reconfiguration/booting.

-JP