SCSI RDMA Protocol (SRP) Target driver for Linux
=================================================

SRP Target driver is designed to work directly on top of OpenFabrics
OFED-1.x software stack (http://www.openfabrics.org) or Infiniband
drivers in Linux kernel tree (kernel.org). It also interfaces with 
Generic SCSI target mid-level driver - SCST (http://scst.sourceforge.net)

By interfacing with SCST driver we are able to work and  support a lot IO
modes on real or virtual devices in the backend
1. scst_disk  -- interfacing with scsi sub-system to claim and export real
scsi devices ie. disks, hardware raid volumes, tape library as SRP's luns

2. scst_vdisk -- fileio and blockio modes. This allows you to turn software raid
volumes, LVM volumes, IDE disks, and normal files into SRP's luns.

3. NULLIO mode will allow you to measure the performance without sending IOs
to *real* devices


Prerequisites
-------------
1. First it is required to download and install SCST driver. Please
refer to SCST's Internet page http://scst.sourceforge.net for download
and installation instructions. You can also find SCST's design document, 
svn repository development tree and utility tools for basic storage
management

2a. Installation of OFED-1.x (x > 0) with kernel_ib development package rpm
or
2b. Built and installed Linux "vanilla" kernel tree from kernel.org

3. Download SRP target driver and its installation scripts from openfabrics.org
git clone git://git.openfabrics.org/~vu/srpt.git ~/srpt
git clone git://git.openfabrics.org/~vu/srpt_inc ~/srpt_inc

Installation
------------
A. Instruction to included in and built with OFED-1.1 development tree
-----------------------------------------------------------------------
1. cd /usr/local/ofed/srp/openib-1.1
2. patch -p1 < ~/srpt_inc/add_srpt_01.patch 
3. patch -p1 < ~/srpt_inc/add_srpt_02.patch 
4. patch -p1 < ~/srpt_inc/add_srpt_03.patch 
5. cp -r ~/srpt drivers/infiniband/ulp/srpt
6. ./configure --with-srp-target-mod <and any other module if required>
7. make and make install

B. Instruction to be included in and built with OFED-1.2 development tree
--------------------------------------------------------------------------
1. cd ~/ofa_1_2_kernel-2007MMDD-hhmm
2. patch -p1 < ~/srpt_inc/add_srpt_01.patch
3. patch -p1 < ~/srpt_inc/add_srpt_03.patch
4. cp -r ~/srpt drivers/infiniband/ulp/srpt
5. ./configure --with-srp-target-mod <and any other module if required>
6. make and make install

B. Instruction to be included in and built with "vanilla" kernel development tree
----------------------------------------------------------------------------------
1. cd /usr/src/linux-2.6.1x
2. patch -p1 < ~/srpt_inc/add_srpt_03.patch
3. cp -r ~/srpt drivers/infiniband/ulp/srpt
4. configure and build SRP target module driver as normal


How-to run
-----------
1. Please refer to SCST's README for loading scsi_tgt driver and its
dev_handlers drivers (scst_disk, scst_vdisk block or file IO mode, nullio, ...)
2. modprobe ib_srpt

On initiator machines you can manualy do the following steps:
1. modprobe ib_srp
2. ipsrpdm -c (to discover new SRP target)
3. echo <new target info> > /sys/class/infiniband_srp/srp-mthca0-1/add_target
4. fdisk -l (will show new discovered scsi disks)

Example:
Assume that you use port 1 of first HCA in the system ie. mthca0

[root@lab104 ~]# ibsrpdm -c -d /dev/infiniband/umad0
id_ext=0002c90200226cf4,ioc_guid=0002c90200226cf4,dgid=fe800000000000000002c90200226cf5,pkey=ffff,service_id=0002c90200226cf4
[root@lab104 ~]# echo id_ext=0002c90200226cf4,ioc_guid=0002c90200226cf4,dgid=fe800000000000000002c90200226cf5,pkey=ffff,service_id=0002c90200226cf4 > /sys/class/infiniband_srp/srp-mthca0-1/add_target

OR

+ You can edit /etc/infiniband/openib.conf to load srp driver and srp HA daemon
automatically ie. set SRP_LOAD=yes, and SRPHA_ENABLE=yes
+ To set up and use high availability feature you need dm-multipath driver
and multipath tool
+ Please refer to OFED-1.x SRP's user manual for more in-details instructions
on how-to enable/use HA feature


TO DO
------
+ Stress test and stabilize the code
+ Performance tuning
+ Integrate and test with SCST's admin/management tools for LUNs masking/sharing among
initiator hosts
+ Handle QP, shared-RQ, and asynchronous events