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

[Domenico Viggiani]

Hi,
I'm trying to resize a multipath map (an EMC Clariion LUN) but something
goes wrong with ioctl call. 
After resizing LUN by EMC Navisphere, I rescanned four paths using:
 echo "1" > /sys/bus/scsi/drivers/sd/<h>\:<b>\:<t>\:<l>/block/device/rescan
 ...
I noticed (in /var/log/messages) that kernel "sees" new size only for two
paths, surely the active ones (Clariion is an active/passive array).
Then, I trespassed LUN on the other storage processor and rescanned all
paths a second time: all sizes was updated.
But, re-running 'multipath -v2', I got:
 # multipath -v 2
 device-mapper: reload ioctl failed: Invalid argument
I found no other way to make this work but umounting filesystem,
deactivating LVM and ran 'multipath -f ... && multipath -v2' (and then other
regular LVM stuffs).
OS is Red Hat 4.5.

About this, I found this message in archives:
 http://www.redhat.com/archives/dm-devel/2007-August/msg00188.html

Is it confirmed that online resizing with multipath is impossible?

If yes, in my opinion, this is a serious limitation to a serious enterprise
use of Linux.

Thanks in advance for any help
-- 
Domenico Viggiani