[dm-devel] [PATCH 09/10] add disable_changed_wwids option

[Hannes Reinecke]

On 10/29/2016 04:55 AM, Benjamin Marzinski wrote:
> If a LUN on a storage device gets remapped while in-use by multipath,
> it's possible that the multipath device will continue writing to this
> new LUN, causing corruption.  This is not multipath's fault (users
> should go remapping in-use LUNs), but it's possible for multipath to
> detect this and disable IO to the device. If disable_changed_wwids
> is set to "yes", multipathd will detect when a LUN changes wwids when it
> receives the uevent for this, and will disable access to the device
> until the LUN is mapped back.
>
> Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
> ---
>  libmultipath/config.c    |  1 +
>  libmultipath/config.h    |  1 +
>  libmultipath/defaults.h  |  1 +
>  libmultipath/dict.c      |  4 ++++
>  libmultipath/discovery.c | 15 +++++++--------
>  libmultipath/discovery.h |  1 +
>  libmultipath/structs.h   |  1 +
>  multipathd/main.c        | 32 ++++++++++++++++++++++++++++++++
>  8 files changed, 48 insertions(+), 8 deletions(-)
>
Hmm. Not sure if the really buys us anything. By the time we process the 
uevent it might already be too late, and I/O might already have been 
written to that device.
I do agree on the warning, though.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare at suse.de			      +49 911 74053 688
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