Re: sysfs interface sometimes does not get the block device name, for a logged in iSCSI target

[satyajit . deshmukh]

On Sunday, December 16, 2018 at 5:30:29 PM UTC-8, The Lee-Man wrote:
>
> On Friday, December 14, 2018 at 12:13:46 PM UTC-8, Satyajit Deshmukh wrote:
>>
>> Hello,
>>
>> An update on the issue. I could observe that the target entries were not 
>> populated under sysfs.
>>
>> This is for a session that has a valid block device:
>> $ ls /sys/class/iscsi_session/session778/device
>> connection778:0 iscsi_session power target162:0:0 uevent 
>>
>> This is for a session that does not have a valid block device:
>> $ls /sys/class/iscsi_session/session780/device
>> connection780:0 iscsi_session power uevent
>>
>> As we can see, the target... directory is missing.
>> So, an event responsible to create the sysfs entry could not get created.
>>
>> journalctl does not print this info. Is there a way to enable some 
>> debugging, to debug this?
>>
>>
>>
> It seems like the iscsi initiator code in the kernel is not creating the 
> target directory. I will have to look at the code to figure out why. Is 
> there any difference between the two targets? How many targets to you have? 
> What type of targets are they (i.e. hardware, software)?
>
>
There is no difference between the two targets. We have 100s of iSCSI 
targets on a single VM. All of these are software targets.
The target device does get created most of the times.

Another related issue we found is during log outs. In that scenario, the 
block device was not cleanly removed, during the iscsiadm logout command. I 
will share details about that shortly.

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Re: Running iscsiadm in containers

[The Lee-Man]

On Sunday, December 16, 2018 at 5:14:03 PM UTC-8, m...@datera.io wrote:
>
> As a baseline here are the previous threads discussing this issue 
> including the RFC from Chris Leech.
>
> https://groups.google.com/forum/#!msg/open-iscsi/vWbi_LTMEeM/P8-oUDkb14YJ
> https://groups.google.com/forum/#!msg/open-iscsi/kgjck_GixsM/U_FqTbYhCgAJ
>
> I think we should try and move Chris's implementation forward if 
> possible.  Many organizations are hitting real pain-points not having a 
> container-compatible open-iscsi implementation, especially with the advent 
> of the ubiquity of containers within the storage vendor world.
>
> On Tuesday, October 23, 2018 at 9:03:01 AM UTC-7, Shailesh Mittal wrote:
>>
>> Hi there,
>>
>> I understand that it was the topic of discussion earlier. As containers 
>> are getting used more and more to run applications, there are frameworks 
>> like Kubernetes (and more) where the calls to talk to scsi storage devices 
>> are being made through a container.
>>
>> Here, vendors are in flux as they need to execute iscsiadm commands to 
>> connect their iscsi based storage to the application-containers. These 
>> caller modules (responsible for connecting to the remote storage) are 
>> running in the containers and thus have no choice but executing iscsiadm 
>> commands from the containers itself.
>>
>> Is there a well understood way to implement this? I remember the thread 
>> from Chris Leech talking about containerizing iscsid but not sure the 
>> end-result of that. (
>> https://groups.google.com/forum/#!msg/open-iscsi/vWbi_LTMEeM/NdZPh33ed0oJ
>> )
>>
>> Any help/direction here is much appreciated.
>>
>> Thanks,
>> Shailesh Mittal.
>>
>
Yes, after reviewing the thread, I'd like to move forward with these 
changes as well.

Chris, do you have time to move forward with this? I'd be glad to help.

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