[Pkg-iscsi-maintainers] Bug#748940: iscsitarget: "service iscsitaget stop" fails when under load

[Ritesh Raj Sarraf]

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On 05/22/2014 09:37 PM, Craig Barnes wrote:
>> Could you please explain what is "heavy load" here? Is it iSCSI traffic ?
> 
> To simulate heavy load ( it does not need to be too heavy ), I initiated
> 4 dd operations to files on the device, then issued the stop.
> 

I am assuming you are writing to the iscsi devices. If yes, then
there's no reason for this to not fail.

>>
>>>
>>> # service iscsitarget stop
>>> [ ok ] Removing iSCSI enterprise target devices: :.
>>> [ ok ] Stopping iSCSI enterprise target service: :.
>>> [....] Removing iSCSI enterprise target modules: :FATAL: Module
>>> iscsi_trgt is in use.
>>>
>>> Changing etc/init/init.debian to use `rmmod --wait` instead of
>>> `modprobe -r` corrects this issue.
>>
>> We use 'modprobe -r' to ensure that dependencies also get unloaded. With
>> 'rmmod --wait', wouldn't it hang the shutdown sequence ?
> 
> I wasn't able to determine any dependant libraries on my system, if
> there are any in other packages that depend on iscsi_trgt then I would
> be happy to test this and improve my solution.
> 

Yes. THis one does not have any direct dependencies. As practice, I use
modprobe.


> Our deployment has many targets so this is not practical for our use case.
> 
> I can see from the other init implementations that init.debian is the
> only one that unloads the modules, is this still necessary?
> 

The userspace daemon is very basic. The sessions are handled in the
kernel. So when you ask iscsitarget to stop, you want the session also
terminated, for which, we need to unload the module.

I haven't confirmed it on the iscsitarget code but for open-iscsi (the
initiator) that is the case.

-- 
Ritesh Raj Sarraf | http://people.debian.org/~rrs
Debian - The Universal Operating System

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