From: Hannes Reinecke <hare@suse.de>
To: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>,
Keith Busch <keith.busch@wdc.com>,
linux-nvme@lists.infradead.org, Keith Busch <kbusch@kernel.org>,
Daniel Wagner <daniel.wagner@suse.de>
Subject: Re: [PATCHv2] nvme-mpath: delete disk after last connection
Date: Tue, 20 Apr 2021 15:19:10 +0200 [thread overview]
Message-ID: <b5dc2cdf-fcb0-8ffc-8ea9-c77d32561043@suse.de> (raw)
In-Reply-To: <20210420080527.GA21651@lst.de>
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_. 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.
So with this patch we change from stalled I/O (where the user has to
reboot the machine to restore operation) to I/O errors (giving the user
at least a _chance_ to recover).
I can easily consider adding a 'queue_if_no_path' option to allow I/O to
be held even once all paths are disconnected, but that will be enother
patch.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
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next prev parent reply other threads:[~2021-04-20 13:19 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 [this message]
2021-04-20 14:14 ` Keith Busch
2021-04-20 14:39 ` Christoph Hellwig
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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