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From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Hannes Reinecke <hare@suse.de>, Christoph Hellwig <hch@lst.de>,
	Sagi Grimberg <sagi@grimberg.me>,
	Keith Busch <keith.busch@wdc.com>,
	linux-nvme@lists.infradead.org,
	Daniel Wagner <daniel.wagner@suse.de>
Subject: Re: [PATCHv2] nvme-mpath: delete disk after last connection
Date: Tue, 20 Apr 2021 16:39:06 +0200	[thread overview]
Message-ID: <20210420143906.GA19417@lst.de> (raw)
In-Reply-To: <20210420141436.GA14300@redsun51.ssa.fujisawa.hgst.com>

On Tue, Apr 20, 2021 at 11:14:36PM +0900, Keith Busch wrote:
> On Tue, Apr 20, 2021 at 03:19:10PM +0200, Hannes Reinecke wrote:
> > On 4/20/21 10:05 AM, Christoph Hellwig wrote:
> > > On Fri, Apr 16, 2021 at 08:24:11AM +0200, Hannes Reinecke wrote:
> > > > With the proposed patch, the following messages appear:
> > > > 
> > > >   [  227.516807] md/raid1:md0: Disk failure on nvme3n1, disabling device.
> > > >   [  227.516807] md/raid1:md0: Operation continuing on 1 devices.
> > > 
> > > So how is this going to work for e.g. a case where the device
> > > disappear due to resets or fabrics connection problems?  This now
> > > directly teards down the device.
> > > 
> > Yes, that is correct; the nshead will be removed once the last path is
> > _removed_.
> 
> The end result is also how non-multipath nvme behaves, so I think that's
> what users have come to expect.

I'm not sure that is what users expect.  At least the SCSI multipath
setups I've worked do not expect it and ensure the queue_if_no_path
option is set.

> > But key point here is that once the system finds itself in that
> > situation it's impossible to recover, as the refcounts are messed.
> > Even a manual connect call with the same parameter will _not_ restore
> > operation, but rather result in a new namespace.
> 
> I haven't looked at this yet, but is it really not possible to restore
> the original namespace upon the reestablished connection?

It is possible, and in fact is what we do.

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  reply	other threads:[~2021-04-20 14:39 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16  6:24 [PATCHv2] nvme-mpath: delete disk after last connection Hannes Reinecke
2021-04-20  8:05 ` Christoph Hellwig
     [not found]   ` <91f25f95-e5a0-466f-b410-6f6dafdec0a0@email.android.com>
2021-04-20  9:54     ` Christoph Hellwig
2021-04-20 13:19   ` Hannes Reinecke
2021-04-20 14:14     ` Keith Busch
2021-04-20 14:39       ` Christoph Hellwig [this message]
2021-04-20 17:02         ` Hannes Reinecke
2021-04-20 17:16           ` Keith Busch
2021-04-20 20:05         ` Martin Wilck
2021-04-20 16:21       ` Hannes Reinecke
2021-04-20 14:16 ` Keith Busch
2021-05-01 11:59   ` Hannes Reinecke

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