Re: [linux-iscsi-devel] Re: [PATCH RFC] replace ioctl for sysfs take 2

["Scott M. Ferris" <sferris@acm.org>]

James Bottomley wrote:
> On Tue, 2004-09-07 at 15:19, Scott M. Ferris wrote:
>
> > That's not a very helpful analogy, since only SPI and FC-AL resemble a
> > bus, and all of the newer SCSI transports are switched fabrics.
> 
> Well, I'm at a bit of a loss to make it plainer ... a host is somewhere
> you plug your bus  this is an obvious concept even for switched
> fabrics.

So a host is where you plug your (non-existent) bus?  I think it would
be clearer to use terminology from SAM.

> > > In iSCSI that's really the other end point.  Using abstractions
> > > incorrectly (like a single host for the entire iSCSI system) is
> > > bound to end up with problems due to the concept mismatch.
> > 
> > I have trouble understanding your viewpoint.  Your answers to the
> > following questions will hopefully clear things up.
> 
> I doubt it, but I'll try.

Thanks.

> > Do you think Linux hosts should be used in a similar way by all
> > switched SCSI transports (e.g. FC-SW, iSCSI, SAS)?  If not, why not?
> 
> Yes.

I'm glad we agree on that.

> > Do you think switched SCSI transports should allocate one Linux host
> > for each I_T nexus?
> 
> No.

This is exactly why I ask these questions.  The iSCSI driver
developers just implemented this, because they thought this is what
you and Christoph were asking for.  Apparently it's not what you
wanted.

> 
> > Do you think switched SCSI transports should allocate one Linux host
> > for each (SAM-2 or SAM-3) SCSI initiator port?
> 
> Yes.

Thank you.  This is a much clear statement of your intent.

> > Do you think switched SCSI transports should allocate one Linux host
> > for each (SAM-2 or SAM-3) SCSI initiator device?
> 
> No.

Should all drivers that currently use one host for each SCSI initiator
device, and a channel for each initiator port on each device, be
modified to use a host for each initiator port?

Documentation/scsi/scsi_mid_low_api.txt says that a host corresponds
to a SCSI initiator device.  Could someone change that to say SCSI
initiator port instead, since that seems to be the new goal?

-- 
Scott M. Ferris,
sferris@acm.org