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)

NOTES: This SRP Target driver can only compile and work with IB driver
       in Linux vanilla kernel. It does not compile and work with IB
       driver in OFED-1.x packages

       If you want to work with IB driver in OFED-1.x package, you should
       read and follow instruction in README.ofed file


Installation
------------
$ make 
$ make install

To minimize QUEUEFULL conditions, please apply scst_increase_max_tgt_cmds
patch and recompile scst

$ cd ~scst/trunk
$ patch -p0 < srpt/patches/scst_increasa_max_tgt_cmds.patch
$ make scst scst_install srpt srpt_install


How-to run
-----------
A. On srp target machine
1. Please refer to SCST's README for loading scst driver and its
dev_handlers drivers (scst_disk, scst_vdisk block or file IO mode, nullio, ...)

Example 1: working with real back-end scsi disks
a. modprobe scst
b. modprobe scst_disk
c. cat /proc/scsi_tgt/scsi_tgt

ibstor00:~ # cat /proc/scsi_tgt/scsi_tgt 
Device (host:ch:id:lun or name)                             Device handler
0:0:0:0                                                     dev_disk
4:0:0:0                                                     dev_disk
5:0:0:0                                                     dev_disk
6:0:0:0                                                     dev_disk
7:0:0:0                                                     dev_disk

Now you want to exclude the first scsi disk and expose the last 4 scsi disks as
IB/SRP luns for I/O
echo "add 4:0:0:0 0" >/proc/scsi_tgt/groups/Default/devices
echo "add 5:0:0:0 1" >/proc/scsi_tgt/groups/Default/devices
echo "add 6:0:0:0 2" >/proc/scsi_tgt/groups/Default/devices
echo "add 7:0:0:0 3" >/proc/scsi_tgt/groups/Default/devices

Example 2: working with VDISK FILEIO mode (using md0 device and file 10G-file)
a. modprobe scst
b. modprobe scst_vdisk
c. echo "open vdisk0 /dev/md0" > /proc/scsi_tgt/vdisk/vdisk
d. echo "open vdisk1 /10G-file" > /proc/scsi_tgt/vdisk/vdisk
e. echo "add vdisk0 0" >/proc/scsi_tgt/groups/Default/devices
f. echo "add vdisk1 1" >/proc/scsi_tgt/groups/Default/devices

Example 3: working with VDISK BLOCKIO mode (using md0 device, sda, and cciss/c1d0)
a. modprobe scst
b. modprobe scst_vdisk
c. echo "open vdisk0 /dev/md0 BLOCKIO" > /proc/scsi_tgt/vdisk/vdisk
d. echo "open vdisk1 /dev/sda BLOCKIO" > /proc/scsi_tgt/vdisk/vdisk
e. echo "open vdisk2 /dev/cciss/c1d0 BLOCKIO" > /proc/scsi_tgt/vdisk/vdisk
f. echo "add vdisk0 0" >/proc/scsi_tgt/groups/Default/devices
g. echo "add vdisk1 1" >/proc/scsi_tgt/groups/Default/devices
h. echo "add vdisk2 2" >/proc/scsi_tgt/groups/Default/devices

2. modprobe ib_srpt


B. 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