[dm-devel] Resizing multipath maps: reload ioctl failed: Invalid argument

[Tore Anderson]

* Jun'ichi Nomura

> IMO, it's not a design limitation and should be solved in future.

   That's good to know.  Hopefully someone will fix it...

> Current code uses 'no_flush' unconditionally.
> I think it's possible to improve it to do that only when
> queue_if_no_path is enabled.

   It certainly would be an improvement if no_flush and queue_if_no_path
  could be automatically disabled in the short time it will take to
  reload the multipath map with an increased size.  For extra safety the
  tool could also verify that no paths were failed before doing so,
  maybe.  If everything is working fine it seems rather unlikely that all
  paths will fail and all HBA driver timeouts will expire in the second
  it takes to reload the multipath map.

> Hmm, sorry. I misread your first message.
> Since the feature is added after 0.4.7, your problem may be caused
> by other reason.
> The call to dm_task_no_flush() is added after the release of 0.4.7.
> It should be in dm_simplecmd() in libmultipath/devmapper.c.

   Interesting.  I sent an email titled "dm-rdac not working?" earlier
  today, where I described another problem with the RDAC hwhandler that
  also caused I/O errors to propagate up from device-mapper into VFS,
  even though queue_if_no_path was in use.  Is it possible, you think,
  that this misbehaviour was due to having loaded the multipath maps
  using 0.4.7 and therefore without no_flush being set?  (Or in other
  words:  Is 0.4.8 a requirement for queue_if_no_path to work correctly?)

   I found the dm_task_no_flush() call in the 0.4.8 sources, thanks!

Regards
-- 
Tore Anderson