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From: Martin Wilck <mwilck@suse.com>
To: Christophe Varoqui <christophe.varoqui@opensvc.com>
Cc: dm-devel mailing list <dm-devel@redhat.com>,
	Xose Vazquez Perez <xose.vazquez@gmail.com>
Subject: Can we drop 'hardware_handler "1 alua"'?
Date: Tue, 27 Mar 2018 10:56:29 +0200	[thread overview]
Message-ID: <1522140989.13140.12.camel@suse.com> (raw)

hwtable.c has multiple entries that set 'hardware_handler "1 alua"'
explicitly. But the kernel has been auto-attaching the ALUA hwhandler
to devices that support it since 4.3, the only prerequisite being that
scsi_dh_alua is present at device probing time (kernel commits
d95dbff2, d6a32b98). "retain_attached_hwhandler" is also hard-wired
since 4.3. Thus if the above prerequisite is met, there's no point in
setting 'hardware_handler "1 alua"'.

We've recently seen problems with the explicit setting of the alua
hwhandler in the hwtable; if we do this and the device fails ALUA for
whatever reason, setting up the multipath map fails entirely.

Therefore we have reasons to try and remove 'hardware_handler "1 alua"'
from the hwtable. But it could cause regressions in some cases, e.g.
for distributions that don't force-load scsi_dh_alua before device
probing, or for kernels older than 4.3.

Opinions, please.

Martin

-- 
Dr. Martin Wilck <mwilck@suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)

--
dm-devel mailing list
dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel

             reply	other threads:[~2018-03-27  8:56 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-27  8:56 Martin Wilck [this message]
2018-03-27 15:09 ` Can we drop 'hardware_handler "1 alua"'? Benjamin Marzinski
2018-03-27 16:01   ` Xose Vazquez Perez
2018-03-27 15:46 ` Xose Vazquez Perez
2018-03-27 19:39   ` Martin Wilck

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