On 02/20/2016 04:16 PM, Bart Van Assche wrote:
On 02/20/16 00:03, Hannes Reinecke wrote:
Also when using your suggestion the 'access_state' attribute will only
be created _after_ the 'ADD' uevent, making it impossible to use it from
udev events.
Can you give an example in which it would be useful to read the ALUA
state from a udev handler ? I'm not sure such an example exists.
When evaluating the 'access_state' from an uevent we can avoid sending
I/O if the path is unavailable; eg if the path is in 'transitioning' I/O
will be queued until that path becomes available again.
Which means that the uevent will be delayed during udev processing, so
that the event will never be read by multipathing (as it's being invoked
only after udev event processing has finished).
And in extreme cases (like OnTap takeover/giveback) it will even drop
the event completely due to a timeout.
If you're absolutely against it we can drop the 'access_state' patches
(ie patch 20-22) and have them folded into a separate patchset.
That sounds like a good idea to me.
Ok, let's do this.
Martin, can you please ignore patches 20-22 when pulling the patchset?
I'll be resubmitting a new patchset with them once these issues are
sorted out.
Or do you need a new patch submission?
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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