From: James Bottomley <jbottomley@parallels.com>
To: "Jörn Engel" <joern@logfs.org>
Cc: Hannes Reinecke <hare@suse.de>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
Ewan Milne <emilne@redhat.com>,
Ren Mingxin <renmx@cn.fujitsu.com>,
Bart van Assche <bvanassche@acm.org>
Subject: Re: [PATCHv2 0/7] Limit overall SCSI EH runtime
Date: Tue, 2 Jul 2013 16:33:40 +0000 [thread overview]
Message-ID: <1372782820.2821.18.camel@dabdike> (raw)
In-Reply-To: <20130702145809.GA19005@logfs.org>
On Tue, 2013-07-02 at 10:58 -0400, Jörn Engel wrote:
> On Tue, 2 July 2013 06:37:05 +0000, James Bottomley wrote:
> >
> > I don't understand what you're getting at. In a dual HBA situation,
> > whether the second HBA is implicated or not depends on configuration and
> > what the first HBA is doing. If it's just passively lost device state,
> > then the second HBA should continue just fine. If the insane HBA is
>
> If the problem is an insane drive instead of an insane HBA, both HBAs
> will be in roughly the same state at roughly the same time - assuming
> they both send commands to the insane drive. If they now go into
> error handling and effectively shut off all the sane drives at roughly
> the same time, the user is ****ed.
That's handled in device reset, so I don't understand your point.
James
> And we shouldn't require the user to buy better hardware. The whole
> point of a redundant setup is that your plane doesn't crash to the
> ground when one of your two engines fails. If regulations required
> perfect engines, you wouldn't be flying to conferences. They require
> decent engines and enough redundancy that any one can fail at any
> moment.
>
> Computer systems are no different. We can construct a robust system
> from individually less robust components. Requiring perfect
> components would be ludicrous. Having a system design where one
> faulty component will reliably bring the system down is equally
> ludicrous. Sadly that is also the state of today's scsi stack.
>
> This is not a theoretical problem, btw. We currently carry some
> patches to solve it for us. They are not applicable for mainline in
> their current state - we support a lot less hardware diversity. But
> trust me, we didn't create them on a whim. ;)
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next prev parent reply other threads:[~2013-07-02 16:33 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-01 6:50 [PATCHv2 0/7] Limit overall SCSI EH runtime Hannes Reinecke
2013-07-01 6:50 ` [PATCH 1/7] dpt_i2o: Remove DPTI_STATE_IOCTL Hannes Reinecke
2013-07-01 6:50 ` [PATCH 2/7] dpt_i2o: return SCSI_MLQUEUE_HOST_BUSY when in reset Hannes Reinecke
2013-07-01 6:50 ` [PATCH 3/7] advansys: Remove 'last_reset' references Hannes Reinecke
2013-07-01 6:50 ` [PATCH 4/7] tmscsim: Move 'last_reset' into host structure Hannes Reinecke
2013-07-01 6:50 ` [PATCH 5/7] dc395: Move 'last_reset' into internal " Hannes Reinecke
2013-07-01 6:50 ` [PATCH 6/7] scsi: remove check for 'resetting' Hannes Reinecke
2013-07-01 6:50 ` [PATCH 7/7] scsi: Add 'eh_deadline' to limit SCSI EH runtime Hannes Reinecke
2013-09-20 7:48 ` Ren Mingxin
2013-10-16 19:22 ` James Bottomley
2013-10-17 14:27 ` Ewan Milne
2013-10-23 9:25 ` Hannes Reinecke
2013-10-23 7:46 ` James Bottomley
2013-10-23 9:49 ` Hannes Reinecke
2013-07-01 17:44 ` [PATCHv2 0/7] Limit overall " Jörn Engel
2013-07-01 19:23 ` James Bottomley
2013-07-01 20:55 ` Jörn Engel
2013-07-02 5:48 ` Hannes Reinecke
2013-07-02 6:37 ` James Bottomley
2013-07-02 14:58 ` Jörn Engel
2013-07-02 16:33 ` James Bottomley [this message]
2013-07-02 15:50 ` Jörn Engel
2013-07-10 20:35 ` Ewan Milne
2013-07-12 5:54 ` Ren Mingxin
2013-07-12 13:30 ` Ewan Milne
2013-07-15 10:33 ` Ren Mingxin
2013-07-26 9:52 ` Ren Mingxin
2013-08-07 6:43 ` Ren Mingxin
2013-08-29 13:06 ` Hannes Reinecke
2013-09-24 20:51 ` Ric Wheeler
2013-09-25 5:48 ` Hannes Reinecke
2013-10-02 16:21 ` Hannes Reinecke
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