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From: Hannes Reinecke <hare@suse.de>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>,
	Keith Busch <keith.busch@wdc.com>
Subject: Re: [PATCH 0/2] nvme: fix regression with MD RAID
Date: Wed, 24 Feb 2021 18:10:34 +0100	[thread overview]
Message-ID: <ee9a6a42-a2b9-7076-a78d-6af9f6ecf4dc@suse.de> (raw)
In-Reply-To: <20210224162534.GC9780@lst.de>

On 2/24/21 5:25 PM, Christoph Hellwig wrote:
> I don't see any regression here, even if the new features sound useful.
> 
Have you ever tried MD RAID on nvme-of?
Without this patch MD RAID will _stop_ I/O until the controller reconnects.
If it does. If it doesn't, the controller gets removed (so after some 
300 seconds), and MD RAID will get an I/O error, finally.
But then you reconnect the failed path, and you end up with a 
_different_ nvme namespace device.
Requiring you to do manual handholding get the MD RAID into shape again.

With this patch it 'just works' without any interaction.

One might argue if that constitutes a regression (as it's been the 
behaviour since day 1), but it certainly is impaired functionality as 
compared to other drivers/subsystems like SCSI.
And we can't have that, can we?

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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      reply	other threads:[~2021-02-24 17:10 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-23 11:59 [PATCH 0/2] nvme: fix regression with MD RAID Hannes Reinecke
2021-02-23 11:59 ` [PATCH 1/2] nvme: add 'fail_if_no_path' sysfs attribute Hannes Reinecke
2021-02-23 12:41   ` Minwoo Im
2021-02-24 22:47   ` Sagi Grimberg
2021-02-25  8:10     ` Hannes Reinecke
2021-02-23 11:59 ` [PATCH 2/2] nvme: delete disk when last path is gone Hannes Reinecke
2021-02-23 12:56   ` Minwoo Im
2021-02-23 14:07     ` Hannes Reinecke
2021-02-24 22:40   ` Sagi Grimberg
2021-02-25  8:37     ` Hannes Reinecke
2021-02-24 16:25 ` [PATCH 0/2] nvme: fix regression with MD RAID Christoph Hellwig
2021-02-24 17:10   ` Hannes Reinecke [this message]

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