[dm-devel] [PATCH 13/18] libmultipath: add ignore_new_boot_devs option

[Hannes Reinecke]

On 10/08/2015 09:44 PM, Benjamin Marzinski wrote:
> When multipath relies on the wwids file to determine whether a device is
> a multipath path (with "multipath -c"), it will fail the first time a
> new multipathable device is discovered, since the wwid clearly won't be
> in the wwids file.  This is usually fine.  Multipath will still set
> itself up on the device, and add the wwid to the wwids file. However,
> this causes a race, where multipath won't claim the path immediately,
> and something else may.  Later multipath will try, and possibly succeed
> at, setting itself up on that device.
> 
> I've seen cases where this can cause problems during boot on and
> immediately after install, where multipath racing with LVM on an already
> labelled device can get the machine into a state where boot fails. This
> can be avoided if multipath simply doesn't set itself up on any devices
> that it didn't claim (with "multipath -c") in the initramfs.  It can
> still safely attempt to set itself up on these devices later in boot,
> after the regular filesystem has been set up.
> 
> To allow this, this patch adds a new option, ignore_new_boot_devs.  When
> enabled, this patch simply keeps multipath from being set up on devices
> that aren't already in the wwids file (along with all the other checks
> that multipath already does). This means that only devices that are
> claimed by "multipath -c" will be used by multipath.
> 
> Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> ---
Well, as SUSE is not relying on /etc/wwids during boot we don't have
this issue :-)

Reviewed-by: Hannes Reinecke <hare at suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
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