[LSF/MM TOPIC][ATTEND] T10-PI RDMA offload

[Sagi Grimberg <sagig@dev.mellanox.co.il>]

Hey SCSI (and LSF) folks,

I'd like to propose the following topic for upcoming LSF-MM:

T10-PI standard is becoming more and more appealing for storage and 
cloud solutions.
Since error-detection coding comes with its cost of CPU computation 
overhead,
state-of-the-art ASICs offer the ability to offload T10-PI operations 
(DIF/DIX), examples
are SAS & FC controllers. Recently, the support for T10-PI offload over 
RDMA transactions
was introduced in the Mellanox Connect-IB HCA.

The first building block, RDMA verbs API supporting T10-PI offload was 
submitted over
Linux-rdma (see http://marc.info/?l=linux-rdma&m=138719320307936&w=2). 
Moreover,
we have seen first seeds of T10-PI support in Linux SCSI target entering 
v3.14 (see
http://lwn.net/Articles/579708/) and RDMA offload implementation in iSER 
transport
(see http://www.spinics.net/lists/linux-scsi/msg71128.html). There is 
still some ground to
fill to get protection information support to a full solution over all 
backend devices.

We would like to use LSF-MM platform to to push forward T10-PI support 
end-to-end which
requires Linux SCSI Target core level support along with transport level 
support in iSER and SRP
(and also FCoE in the future) and over to the Initiator side transports.

Discussion topics:
- Introduce T10-PI offload RDMA verbs and how are used in storage 
applications.
- Discuss effects of DIX1.1 (currently a draft) in Target implementation 
(core level -> transport level -> HW level).
- Discuss T10-PI Type 4 (16-byte DIF) status and possible implications 
on Target & Initiator implementation down to HW level.
- Discuss Current Limitations that T10-PI RDMA offload poses on iSCSI 
protocol (ImmediateData, UnsolDataOut) and if/how
   they can be solved.
- What-ever else comes to mind...

Thanks,
Sagi.