[ewg][PATCH][0/2] SRP multipath failover within 60 seconds,

[Vu Pham]

EXTRA NOTES:

1. pull cable/ plug back in (or ibportstate disable/enable)
a. Within 30 seconds I/Os resume on the same path (with same 
cm_id, qp and cq)
b. Within 30-45 seconds, I/Os resume on the same path (with 
new cm_id, qp and cq)
c. >45 seconds, I/Os fail-over to next path

2. After running test for a while, I stop the test, run 
*multipath -F* and unload ib_srp module. With RHEL 5 & 5.1, 
I can unload ib_srp cleanly; however, I got *srp is in use* 
error in SLES 10 sp1

    -vu

> The following patches assist SRP/dm-multipath to failover within 60 
> seconds (bugzilla #577) without data corruption, read/write error
> 
> 1. srp_disconnect_without_wait.patch - srp send disconnect request  
> without waiting for CM timewait exit event since srp current does not 
> re-use the cm_id and qp/cq of a connection (patch 
> srp_1_recreate_at_reconnect.patch already in kernel_patches/fixes 
> recreate the cmid, qp/cq for a connection at reconnect)
> 2. srp_qp_in_err_timer_reconnect_target.patch - when detecting a 
> post_send/post_receive error, srp set qp_in_error, set a timer to 
> reconnect to target, return SCSI_MLQUEUE_HOST_BUSY to lock the queue, 
> and return DID_NO_CONNECT when target state is DEAD or REMOVED
> 
> Here is my multipath.conf
> defaults {
>        udev_dir                /dev
>        polling_interval        5
>        selector                "round-robin 0"
>        path_grouping_policy    multibus
>        getuid_callout          "/sbin/scsi_id -g -u -s /block/%n"
>        prio_callout            /bin/true
>        path_checker            readsector0
>        rr_min_io               100
>        rr_weight               priorities
>        failback                immediate
>        no_path_retry           5
>        user_friendly_names     no
> }
> I also set srp_daemon.sh to rescan fabric every 60 seconds (instead of 
> 300 secs as default setting)
> 
> I ran data integrity test to /dev/mapper/<devices> and {disable path 1, 
> sleep 90, enable path 1, sleep 60, disable path 2, sleep 90, enable path 
> 2, sleep 60} in the loop
> 
> RHEL5, 5.1 work very well (no data corruption, read/write failure report)
> For SLES 10 sp1, it work well as long as I run *multipath* every 60 
> secs. I think that I mis-configured the multipathd somehow (Here is how 
> I set it up: using the same multipath.conf above, chkconfig 
> boot.multipath on and chkconf multipathd on)
> 
>   -vu
> 
> 
> 
> 
> 
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