From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Reed Subject: Re: [PATCH 1/1] ib_srp: Infiniband srp fast failover patch. Date: Tue, 29 May 2012 14:51:58 -0700 Message-ID: <4FC544FE.3000204@sgi.com> References: <4FC53AAA.3060203@ddn.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4FC53AAA.3060203@ddn.com> Sender: linux-kernel-owner@vger.kernel.org To: Karandeep Chahal Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, dillowda@ornl.gov, roland@kernel.org, sean.hefty@intel.com List-Id: linux-rdma@vger.kernel.org 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 >