Re: [PATCH 1/1] ib_srp: Infiniband srp fast failover patch.

Karandeep Chahal
2012-05-29T22:27:46Z

Hi Michael,

Yes, I tried reconnecting the targets and removing reinserting ib-srp.

Thanks
Karan

On 05/29/2012 05:51 PM, Michael Reed wrote:
> Did you subsequently reconnect the target and confirm appropriate behavior?
>
>
> On 05/29/2012 02:07 PM, Karandeep Chahal wrote:
>> Subject: [PATCH] Infiniband srp fast failover patch. Currently ib_srp does
>> not do anything on receiving a DREQ from the target, it
>> only sends a response back. Further it also does not
>> monitor port (down) events. I have patched srp to remove
>> scsi devices when a port down event is received or if the
>> target sends a DREQ. Currently even though the target
>> notifies the initiator of its intentions of going away, the
>> initiator ignores that information. Later the initiator
>> gets upset when the devices "suddenly" disappear resulting
>> in srp initiating an error recovery process which takes a
>> long time. This caused high failover latencies as compared
>> to fibre channel. In my experiments with RHEL 6.0 and 6.2 I
>> encountered failover time that exceeded 2 minutes and 20
>> seconds (despite tweaking /etc/multipath.conf and
>> /sys/block/<>/timeout). With this patch the failover takes
>> 30 seconds. I have tested this patch with and without a
>> switch.
>>
>> Yours, etc.
>> Karan
>>