Target ID

Matthew Jacob mjacob at feral.com
Thu Oct 28 13:24:27 PDT 1999


* From the T10 Reflector (t10 at t10.org), posted by:
* Matthew Jacob <mjacob at feral.com>
*



On Thu, 28 Oct 1999, Ericson, George wrote:

> Mathew,
> 
> The environment I'm, insterested in is hot-swap hardware implementing
> multiple Logical Units underneath a single multi-ported target.
> 
> In your scenario, you say the HBA driver will remap as appropriate.
> 
> Question: Remap what? (Logical Units to Device Names, or something
> else?  If Logical Units, are you relying on the Device ID in the Vital
> Products Data Page, or something else?)


Perhaps I misunderstood the usage of Target Identifier. In my scenarios 
the HBA will keep the crusty old 'target id' as constant (from system
boot to system boot), no matter what the actual addressing on the same
bus. Over time VPD or WWN identification of the TARGET will become the
preferred mechanism in the OS with target or port id just being one of
many possible current route identifiers, but not anytime soon is my guess.

LUN level persistent addressing is not something I've tried to design for 
yet. Sorry if I was being a bonehead here.

> 
> 
> -----Original Message-----
> From: Matthew Jacob [mailto:mjacob at feral.com]
> Sent: Thursday, October 28, 1999 3:23 PM
> To: Ericson, George
> Cc: 'T10 at T10.org'
> Subject: Re: Target ID
> 
> 
> 
> 
> On Thu, 28 Oct 1999, Ericson, George wrote:
> 
> > * From the T10 Reflector (t10 at t10.org), posted by:
> > * "Ericson, George" <gericson at clariion.com>
> > *
> > Request for Comments:
> >  The Target Identifier specified in SAM is an Upper Level Protocol
> > entity.  There does not seem to be a well defined means to return the
> > Target Identifier?  There is a point of view that Target Identifier is
> > a different entity from the Port ID.  Especially for Multi-Port
> > Targets.  Is there concensus on that point?
> >  Is there a consensus view on the persistance of this Target ID in the
> >
> > face of Hot-Swap issues on both the HBA and Device level?  For
> > instance, if a controller card within a Target Device is hot-swapped,
> > and that card happens to have a SCSI Port (regardless of Lower Level
> > Protocol: SPI or FC or ...).  Does the Target Device ID stay the same
> > or change?
> 
> I don't know what others are planning, but the "Target Device ID" is being
> treated by me in Linux, FreeBSD, NetBSD and OpenBSD and for some Solaris
> work as purely an artifact of legacy ULP software layers. As such, it's a
> fixed entity. If the actual AL_PA or Port changes, the HBA driver will
> remap as appropriate.
> 

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