On 04/22/2014 02:10 AM, Cale, Yonatan wrote:
> Hi Mike,
> Answers are in your message below:
> 
> -----Original Message-----
> From: Mike Christie [mailto:[email protected]] 
> Sent: Tuesday, April 22, 2014 12:38 AM
> To: Cale, Yonatan
> Cc: [email protected]; [email protected]
> Subject: Re: Target reboot -> iscsiadm rescan Stuck
> 
>> Do you have some module that is hooking into the scsi layer or iscsi 
>> modules? Just wondering what the "sim_try_to_abort_cmd" call is. Where are 
>> you hooking in? 
> "sim" is our module that handles iscsi data-path. We hook for notifications 
> in order to know if we should cancel a command (we didn't find this in 
> open-iscsi, this is a little off-topic, but does open-iscsi know how to abort 
> commands by itself?)

I do not think it does what you are asking. The iscsi layer implements
some scsi_host_template callouts to abort a command or do a lun or
target reset. When the scsi command timer fires, the scsi layer will
call those callouts to have the iscsi layer send the TMF.


> I think this sould have nothing to do with the iscsiadm control path. I'll 
> verify this with our sim guys (they are on vacation).
> 
>> Have you also modified the iscsi tools?
> No. I'll verify this too, but it's highly unlikely.
> 
>> During this test, is the target able to respond to iscsi level IO, but just 
>> not scsi commands? I see iscsi nops are successful, but the scsi scan 
>> related commands like REPORT_LUNS are never replied to by the target. The 
>> scsi error handler then runs. Some aborts work, but eventually we do not get 
>> a response to one, and that results in the device getting offlined. I then 
>> see something is trying to delete the session (the upstream iscsi tools 
>> would normally not do this).
> The target is a VNX being (partially) rebooted. I don't know for sure what it 
> can/can't do during that reboot, but I think it can't answer NOP commands 
> either:
> I did some investigation of the tcpdump I sent you, and I can see that at 
> some point (packet #1682, time~=38sec), there are no more packets FROM 
> 10.76.18.23, which is the IP of the VNX-SP that I am rebooting. This includes 
> NOP iSCSI commands which are also not sent anymore.
> 
>> It then looks like we hit a bug in the scsi layer. The scsi layer keeps 
>> trying to send a inquiry, but because we are deleting the session, the iscsi 
>> layer fails the command with DID_TRANSPORT_FAILFAST. This then goes on for 
>> minutes until you stop taking the trace.
> 
>> To debug this some more, we will need to get some scsi layer tracing.
>> Did you run that scsi_logging_level command? 
> I did " scsi_logging_level --scan 7 --error 7 -s" (Unless I made a mistake? 
> Do you think this command wasn't run?)
> 

I did not see any extra scsi layer scanning in the log you sent.

>> Could you also check the current kernel?
> I don't understand what you are asking for. The kernel version? 3.0.56
> 

I just meant try a newer kernel like 3.14.

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