[Stgt-devel] User-mode iSER

Tom Tucker tom
Tue Aug 1 15:09:13 CEST 2006


On Tue, 2006-08-01 at 11:37 +0900, FUJITA Tomonori wrote:
> From: Tom Tucker <tom at opengridcomputing.com>
> Subject: [Stgt-devel] User-mode iSER
> Date: Mon, 31 Jul 2006 16:05:23 -0500
> 
> > Tomo:
> > 
> > I heard a rumor that moving even more of the iSER target design into
> > user mode was considered at the OLS. I think this is a very interesting
> > idea and would like to know what you and others think of this in general
> > and if there are any specific issues that people think make this
> > difficult.
> 
> Yeah, we thought about that.
> 
> It's still not clear that tgt iSCSI target driver (*1) is accepted to
> mainline. We can use lots of parts of open-iscsi code for it, however,
> you can say that iSCSI target software can be implemented in user
> space.

Also, won't a user-mode approach support virtual target devices more
easily? 

> 
> Mike said that returning from vacation, he clean up and submit the
> iSCSI target driver to scsi-ml for discussion.

Do you know When does he gets back?

> 
> If we fail to put it into mainline, I'll implement iscsi target
> software in user space, which uses tgt user-space code (SCSI
> processing, management, etc). So, is it possible that we integrate
> iSER into user-space iSCSI target software?

Yes it is possible to use iSER as a user-mode transport. In fact, iSER
supports kernel-bypass, so there is no additional overhead vs. i/o in
the kernel. 


> 
> *1) the iSCSI (tcp) target driver for tgt (which partially works)
> 
> svn+ssh://svn.berlios.de/svnroot/repos/stgt/trunk/istgt
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