From: Christoph Hellwig <hch@lst.de>
To: Martin Wilck <mwilck@suse.com>
Cc: Mike Snitzer <snitzer@redhat.com>,
linux-scsi@vger.kernel.org, Daniel Wagner <dwagner@suse.de>,
emilne@redhat.com, linux-block@vger.kernel.org,
dm-devel@redhat.com, Paolo Bonzini <pbonzini@redhat.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
nkoenig@redhat.com, Bart Van Assche <Bart.VanAssche@sandisk.com>,
Christoph Hellwig <hch@lst.de>,
Alasdair G Kergon <agk@redhat.com>
Subject: Re: [dm-devel] [PATCH v5 3/3] dm mpath: add CONFIG_DM_MULTIPATH_SG_IO - failover for SG_IO
Date: Thu, 1 Jul 2021 13:34:42 +0200 [thread overview]
Message-ID: <20210701113442.GA10793@lst.de> (raw)
In-Reply-To: <de1e3dcbd26a4c680b27b557ea5384ba40fc7575.camel@suse.com>
On Thu, Jul 01, 2021 at 12:35:53PM +0200, Martin Wilck wrote:
> I respectfully disagree. Users of dm-multipath devices expect that IO
> succeeds as long as there's at least one healthy path. This is a
> fundamental property of multipath devices. Whether IO is sent
> "normally" or via SG_IO doesn't make a difference wrt this expectation.
If you have those (pretty reasonable) expections don't use SG_IO.
That is what the regular read/write path is for. SG_IO gives you
raw access to the SCSI logic unit, and you get to keep the pieces
if anything goes wrong.
--
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dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel
next prev parent reply other threads:[~2021-07-01 11:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-28 15:15 [dm-devel] [PATCH v5 0/3] scsi/dm: dm_blk_ioctl(): implement failover for SG_IO on dm-multipath mwilck
2021-06-28 15:15 ` [dm-devel] [PATCH v5 1/3] scsi: scsi_ioctl: export __scsi_result_to_blk_status() mwilck
2021-06-28 15:15 ` [dm-devel] [PATCH v5 2/3] scsi: scsi_ioctl: add sg_io_to_blk_status() mwilck
2021-06-28 15:15 ` [dm-devel] [PATCH v5 3/3] dm mpath: add CONFIG_DM_MULTIPATH_SG_IO - failover for SG_IO mwilck
2021-07-01 7:56 ` Christoph Hellwig
2021-07-01 10:35 ` Martin Wilck
2021-07-01 11:34 ` Christoph Hellwig [this message]
2021-07-02 14:21 ` Martin Wilck
2021-07-05 13:02 ` Paolo Bonzini
2021-07-05 13:11 ` Hannes Reinecke
2021-07-05 13:48 ` Martin Wilck
2021-07-06 10:13 ` Paolo Bonzini
2021-07-01 11:06 ` Paolo Bonzini
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