Re: [PATCH][RFC 21/23]: iSCSI target driver

Nicholas A. Bellinger
2008-12-11T23:00:34Z

On Thu, 2008-12-11 at 14:55 -0800, Nicholas A. Bellinger wrote:
> On Wed, 2008-12-10 at 22:01 +0300, Vladislav Bolkhovitin wrote:
> > This patch contains iSCSI-SCST target driver. This driver is a heavily
> > modified forked with all respects IET
> > (http://iscsitarget.sourceforge.net). Modifications were aimed to make a
> > clearer, more reviewable and maintainable code as well as to fix many
> > problems and make many improvements. See
> > http://scst.sourceforge.net/target_iscsi.html for more details.
> >
> > It has split user/kernel space architecture, where all management,
> > sessions creation, parameters negotiation, etc. made in user space and
> > data are transferred in the kernel space. Such architecture for iSCSI
> > processing was many times acknowledged as the right one. Particularly,
> > in-kernel iSCSI initiator (open-iscsi) has such architecture.
> >
>
> Just as with the Open/iSCSI Initiator, IMHO I believe the split
> architecture design is difficult both to improve, debug and maintain,
> and provides *ZERO* additional benefit in the context of traditional
> iSCSI target mode for doing login and connection/session setup in
> userspace.
>
> Also, I appericate that you spent alot of time porting over IET code to
> your engine, but during our previous discussion you did not seem
> terribly interested in validation against core-iscsi-dv
> (http://linux-iscsi.org/index.php/Core-iscsi-dv) to test RFC-3720
> interopt and stability. Because the Core-iSCSI Initiator supports every
> possible parameter combination up to ErrorRecoveryLevel=0 defined in
> RFC-3720, the Core-iSCSI-Dv tests can run badblocks (or any too) to
> check data integrity for *EVERY* possible traditional iSCSI key
> combination and functionality for your iSCSI-SCST work, and any type of
> serious iSCSI-SCST production deployments.
>
> Until you can at least do that to prove both the stability and
> completeness of your iSCSI Target stack up to RFC-3720
> ErrorRecoveryLevel=0, I don't think this code makes sense for any type
> of mainline acceptance. Also, I would appericate if you could stop the
> handwaving about MC/S and ErrorRecoveryLevel=2 as well. MC/S (multiple
> connection paths for iSCSI/TCP, not necessary with multiple assoication
> LIO-Target SCTP) and ERL=2 (OS independent fabric recovery) is available
> in both RFC-3720 (Traditional iSCSI) and RFC-5045 (iSER for iWARP and
> IB).
>

That was RFC-5046 for iSER note btw, RFC-5045 is the actual case for
RDMA/DDP over TCP and the Stream Control Transfer Protocol (SCTP).

Regards,

--nab

> Trying to argue against implementing the complete iSCSI RFC
> functionality (like some folks did during the early Open/iSCSI days)
> that customers and users *WANT* now is going to fall of deaf ears.
> Please understand that they are going to be many, many different iSCSi
> Initiators connecting to the upstream iSCSI Target Core infrastructure,
> and trying to rush in an incomplete iSCSI Target $FABRIC_MOD
> implementation benefits anyone.
>
> Regards,
>
> --nab
>
> > Signed-off-by: Vladislav Bolkhovitin <vst@vlnb.net>
> > ---
> > drivers/scst/iscsi-scst/Kconfig | 25
> > drivers/scst/iscsi-scst/Makefile | 6
> > drivers/scst/iscsi-scst/config.c | 597 +++++++
> > drivers/scst/iscsi-scst/conn.c | 488 +++++
> > drivers/scst/iscsi-scst/digest.c | 221 ++
> > drivers/scst/iscsi-scst/digest.h | 31
> > drivers/scst/iscsi-scst/event.c | 116 +
> > drivers/scst/iscsi-scst/iscsi.c | 3066 ++++++++++++++++++++++++++++++++++++
> > drivers/scst/iscsi-scst/iscsi.h | 577 ++++++
> > drivers/scst/iscsi-scst/iscsi_dbg.h | 73
> > drivers/scst/iscsi-scst/iscsi_hdr.h | 517 ++++++
> > drivers/scst/iscsi-scst/nthread.c | 1522 +++++++++++++++++
> > drivers/scst/iscsi-scst/param.c | 263 +++
> > drivers/scst/iscsi-scst/session.c | 210 ++
> > drivers/scst/iscsi-scst/target.c | 306 +++
> > include/scst/iscsi_scst.h | 156 +
> > include/scst/iscsi_scst_ver.h | 16
> > 17 files changed, 8190 insertions(+)
> >
> > The patch is too big to be submitted inline. You can find it in
> > http://scst.sourceforge.net/patches/iscsi-scst.diff
> >
> >
> >
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