From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vu Pham Subject: Re: [ofa-general][PATCH 3/4] SRP fail-over faster Date: Thu, 15 Oct 2009 09:23:36 -0700 Message-ID: <4AD74C88.8030604@mellanox.com> References: <4AD3B453.3030109@mellanox.com> <4AD63681.6080901@mellanox.com> <4AD63DB1.3060906@mellanox.com> <1255570760.13845.4.camel@obelisk.thedillows.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1255570760.13845.4.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: David Dillow Cc: Roland Dreier , Linux RDMA list List-Id: linux-rdma@vger.kernel.org David Dillow wrote: > On Wed, 2009-10-14 at 15:47 -0700, Roland Dreier wrote: > >>>> > First it does not make sense for user to set it below 60; therefore, >>>> >> > > > it is forced to have 60 and above >> >> > > Why not? A minute seems to be a really long time given the point of >> > > these patches is supposed to be failing over faster. Surely we can tell >> > > if a path really failed sooner than 60 seconds on an IB fabric. >> >> > When we fail-over, it will cause the luns ownership transfer in >> > target/storage. It's undesirable op unless necessary >> > Target/storage most likely can reboot and come back within 60 seconds >> > We don't want to create the situation of path bouncing >> >> OK, I can see why in some (many) situations it makes sense to wait a >> while before reporting a target as gone. But why do we hard code the >> policy of a minimum timeout of 60 seconds in the kernel? Why not a >> minimum of 120 seconds? What if I know my storage is guaranteed to >> reboot in 2 seconds -- why can't I have a timeout of 5 seconds? >> >> You haven't really explained where the magic number of 60 seconds comes from. >> > > On that note, does this have to be a module parameter -- what if I have > connections to different devices, that have different reboot guarantees? > > It can be tuned down to target/device level instead of module parameter. What do you think, Roland? It can be a param. in login string and stored in target structure. > And if I really want a timeout of less than 60 seconds, why should I > have to patch my kernel? > > Then target parameter would be the right approach. > And if I want to disable this completely? > Unless these patches are bad and affect the stability of the driver, why do you want to disable it? If you don't use multipath/device-mapper and use /dev/sd**, everything will be same -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html