From: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
To: Or Gerlitz <or.gerlitz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
David Dillow <dillowda-1Heg1YXhbW8@public.gmane.org>,
Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
Subject: Re: [PATCH 00/19, v5] Make ib_srp better suited for H.A. purposes
Date: Tue, 13 Nov 2012 22:30:41 +0100 [thread overview]
Message-ID: <50A2BC01.40609@acm.org> (raw)
In-Reply-To: <CAJZOPZJXdLRH9NPCt0snGNP8LKODO+phtV7uts6Vj-gxEEjpsw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On 11/13/12 22:04, Or Gerlitz wrote:
> Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org> wrote:
>> On 11/12/12 23:36, Or Gerlitz wrote:
>
>> This patch series reduces path failover time significantly. Instead of
>> having to wait until the SCSI error handler has finished recovery,
>
> When a SCSI device is selected by mpath and used as a path, aren't failed
> commands returned back to the mpath driver for possibly re-submission over
> a different path?
The advantage of having a configurable fast_io_fail_tmo parameter is
that this parameter can be configured to a smaller value than the SCSI
timeout and hence that failover mechanisms in higher layers (dm and
multipathd) are triggered more quickly if an I/O error is encountered.
>> multipathd switches paths as soon as fast_fail_tmo has elapsed. Also, SCSI
>> hosts that correspond to failed paths are removed. With the upstream SRP
>> initiator and when triggering path failover repeatedly after some time
>> hundreds of obsolete SCSI hosts are present.
>>
>>>> - Dropped the patches for integration with multipathd.
>>>
>>> can you explain this please? are these non SRP patches which we
>>> submitted/accepted
>>> through another maintainer? can you point on the upstream commits?
>>
>>
>> With that comment I was referring to the dev_loss_tmo and fast_io_fail_tmo
>> sysfs variables that had been dropped in v2 of this patch set but that have
>> been reintroduced in v3 of this patch set. If these parameters have been set
>> in /etc/multipath.conf then multipathd passes these on to the block driver
>> (ib_srp in this case), at least the block driver provides the dev_loss_tmo
>> and fast_io_fail_tmo sysfs attributes.
>
> So these are attributes you added to the block layer, or to SRP? I'm
> not clear on that.
These attributes have been added to the SRP transport layer. Since the
ib_srp driver registers itself with the SRP transport layer the SRP
transport layer creates these two attributes for the ib_srp driver. This
is similar to how the FC transport layer creates these attributes for FC
initiator drivers.
Bart.
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next prev parent reply other threads:[~2012-11-13 21:30 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-26 12:44 [PATCH 00/19, v5] Make ib_srp better suited for H.A. purposes Bart Van Assche
2012-10-26 12:52 ` [PATCH 11/19] srp_transport: Fix attribute registration Bart Van Assche
2012-10-26 12:54 ` [PATCH 13/19] srp_transport: Document sysfs attributes Bart Van Assche
2012-10-26 12:55 ` [PATCH 14/19] ib_srp: Allow SRP disconnect through sysfs Bart Van Assche
[not found] ` <508A85BB.1000505-HInyCGIudOg@public.gmane.org>
2012-10-26 12:45 ` [PATCH 01/19] ib_srp: Enlarge block layer timeout Bart Van Assche
2012-10-26 12:46 ` [PATCH 02/19] ib_srp: Eliminate state SRP_TARGET_CONNECTING Bart Van Assche
2012-10-26 12:46 ` [PATCH 03/19] ib_srp: Introduce srp_handle_qp_err() Bart Van Assche
2012-10-26 12:47 ` [PATCH 04/19] ib_srp: Suppress superfluous error messages Bart Van Assche
2012-10-26 12:48 ` [PATCH 05/19] ib_srp: Avoid that SCSI error handling causes trouble Bart Van Assche
2012-10-26 12:49 ` [PATCH 06/19] ib_srp: Introduce the helper function srp_remove_target() Bart Van Assche
2012-10-26 12:49 ` [PATCH 07/19] ib_srp: Eliminate state SRP_TARGET_DEAD Bart Van Assche
2012-10-26 12:50 ` [PATCH 08/19] ib_srp: Keep processing commands during host removal Bart Van Assche
2012-10-26 12:50 ` [PATCH 09/19] ib_srp: Make srp_disconnect_target() wait for IB completions Bart Van Assche
2012-10-26 12:51 ` [PATCH 10/19] ib_srp: Document sysfs attributes Bart Van Assche
2012-10-26 12:53 ` [PATCH 12/19] srp_transport: Simplify attribute initialization code Bart Van Assche
2012-10-26 12:55 ` [PATCH 15/19] ib_srp: Maintain a single connection per I_T nexus Bart Van Assche
2012-10-26 12:56 ` [PATCH 16/19] srp_transport: Add transport layer error handling Bart Van Assche
2012-10-26 12:57 ` [PATCH 17/19] ib_srp: Add dev_loss_tmo support Bart Van Assche
2012-10-26 12:58 ` [PATCH 18/19] ib_srp: Remove SCSI devices upon port down event Bart Van Assche
[not found] ` <508A88D8.2050905-HInyCGIudOg@public.gmane.org>
2012-11-12 22:40 ` Or Gerlitz
[not found] ` <CAJZOPZL8mKU2MsrPPACvWjiA59aGnWDj0HNTQQNhbDrMsE0+Tg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 8:59 ` Bart Van Assche
[not found] ` <50A20C03.9040607-HInyCGIudOg@public.gmane.org>
2012-11-13 20:54 ` Or Gerlitz
[not found] ` <CAJZOPZ+PiDQ6GYLkDO4MaPTDxLr2XDMn8q3gTaX-COx04PSegg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 21:20 ` Bart Van Assche
[not found] ` <50A2B989.8000600-HInyCGIudOg@public.gmane.org>
2012-11-13 21:23 ` Or Gerlitz
[not found] ` <CAJZOPZLSPz7f99tj2w-79sPbibrHP3WZY_ct0Cq07Q1so54kFQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 21:35 ` Bart Van Assche
2012-10-26 12:58 ` [PATCH 19/19] scsi_transport_srp: Fail I/O faster Bart Van Assche
2012-11-12 22:36 ` [PATCH 00/19, v5] Make ib_srp better suited for H.A. purposes Or Gerlitz
[not found] ` <CAJZOPZJPQkJ-kkW3ro9sRJXQJg_Yz_tjoJ1Rwb=XEePO3j_iJw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 8:41 ` Bart Van Assche
[not found] ` <50A207D5.6060207-HInyCGIudOg@public.gmane.org>
2012-11-13 21:04 ` Or Gerlitz
[not found] ` <CAJZOPZJXdLRH9NPCt0snGNP8LKODO+phtV7uts6Vj-gxEEjpsw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 21:30 ` Bart Van Assche [this message]
[not found] ` <50A2BC01.40609-HInyCGIudOg@public.gmane.org>
2012-11-13 21:41 ` Or Gerlitz
[not found] ` <CAJZOPZLQ8B9UGvGdM5LvA6r+XDARO5BXGoMmtdSH6+8EMyMaXw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 22:35 ` Bart Van Assche
2012-11-12 22:51 ` Or Gerlitz
[not found] ` <CAJZOPZLHg84M3RUV00itGSGUZsigW0yw=TLOe6K63mUXH5v1pQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 8:34 ` Bart Van Assche
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