iSCSI logout hangs LVM

[Bryn M. Reeves <bmr@redhat.com>]

Dave Wysochanski wrote:
> On Wed, 2009-01-14 at 22:23 -0700, Ty! Boyack wrote:
>> This is all being done on a Fedora 9 boxes with updated packages:
>> lvm2-2.02.33-11.fc9.x86_64
>> iscsi-initiator-utils-6.2.0.870-1.0.fc9.x86_64
>> device-mapper-1.02.24-11.fc9.x86_64
>> udev-124-2.fc9.x86_64
>> kernel-2.6.27.9-73.fc9.x86_64
>>
>> I would appreciate any thoughts or suggestion on this!
>>
> 
> You need to make sure iscsi and multipath are setup properly to
> eventually fail the IO.  I believe the README and/or config files in
> these projects describe the settings needed.

Or remove the multipath maps for these devices *before* logging out of 
the target. This is a common mistake with multipath - when you're 
removing storage, the ordering should normally be:

- unmount file systems / stop applications using the device
- flush multipath map(s) (-f/-F)
- remove underlying path devices (iSCSI logout etc)

If this isn't possible, there's a feature in the RHEL builds of 
multipath-tools named "flush_on_last_del" which may help you here. It 
will disable queueing for the multipath target when the last path to 
it disappears, preventing I/O from hanging forever on the missing devices.

Regards,
Bryn.