Re: [storm] Removing iSCSI Markers?

Caitlin Bestler <cait@asomi.com> Thu, 01 April 2010 02:44 UTC

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Subject: Re: [storm] Removing iSCSI Markers?
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On Mar 30, 2010, at 10:11 AM, Asgeir Eiriksson wrote:

> Mallikarjun,
>  
> I was referring to the MPA-version of markers only, and the Chelsio iSCSI HBA do
> not support iSCSI markers.
>  
> Regards,
>  
> 'Asgeir
>  
> > From: cbm@chadalapaka.com
> > To: marke@muttsnuts.com; storm@ietf.org
> > Date: Tue, 30 Mar 2010 09:42:07 -0700
> > Subject: Re: [storm] Removing iSCSI Markers?
> > 
> > I believe out of order placement continues to be critical for efficient
> > RNIC/DDP implementations, and markers play a role there.
> > 
> > Having said that, IMHO, that is not exactly the question we should tackle on
> > this thread.
> > 
> > We should focus on these two iSCSI-centric questions: 
> > 
> > 1) Are there implementations out there that implement iSCSI Markers *as
> > defined by RFC 3720*? (Asgeir may have answered this question as "yes", but
> > he referenced an RNIC so I am not sure if he's referring to the MPA-version
> > of markers or iSCSI key-driven markers)
> > 
> > 2) If "yes" to #1, if we drop iSCSI Markers in the new Consolidated draft,
> > would that cause problems to any "applications" - i.e. iSCSI and SCSI stacks
> > in either commercial O/S or proprietary embedded implementations?
> > 
> > 
> > If the answer to the second question is "No", we can go ahead and drop it
> > from the iSCSI Consolidated draft, independent of MPA/DDP/RDMAP.
> > 
> > Thanks.
> > 
> > Mallikarjun
> > 
> > 
> > 
> 


If there are deployed iSCSI HBA/CNICs that fully support markers then by all means we should
commend them for doing so and not leave them stranded.

But if there are none then keeping iSCSI markers really makes no sense. iSER provides a better
solution for out-of-order data placement. There's no point in backing two "future" options, it's
better to consolidate on one.

If your network needs to support out-of-order data placement for SCSI, you should be looking
for a NIC that supports iSER/iWARP.


--
Caitlin Bestler
cait@asomi.com
http://www.asomi.com/CaitlinBestlerResume.html