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

Michael Reed
2012-05-29T22:53:05Z

Thank you for clarifying!

On 05/29/2012 03:27 PM, Karandeep Chahal wrote:
> 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
>>>
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