[stgt] help tgt segfault

[Tomasz Chmielewski]

FUJITA Tomonori schrieb:
> On Tue, 03 Feb 2009 10:36:22 +0100
> Tomasz Chmielewski <mangoo at wpkg.org> wrote:
> 
>> FUJITA Tomonori schrieb:
>>
>>>> If you could provide me some "debug" version of tgtd, maybe?
>>> The following message showed up _after_ the segfault, right?
>>>
>>> Did you see any message _before_ the segfault?
>> Once again - I connected the initiator at about 10:27, started copying the files.
>> Before the segfault there were messages below (this target has 3 connected initiators from
>> 2 machines / IP addresses).
>> Hope it helps, let me know if you need any more info.
> 
> Let me make sure about your configuration,
> 
> 1) send the output of `tgtadm --op show --mode target` before starting
> copying the files.

Target 1: iqn.2006-08.net.syneticon:superthecus.backup   
    System information:                                  
        Driver: iscsi                                    
        State: ready                                     
    I_T nexus information:                               
        I_T nexus: 2                                     
            Initiator: iqn.2006-12.net.syneticon:server.backup1
            Connection: 0                                      
                IP Address: 192.168.111.173                    
    LUN information:                                           
        LUN: 0                                                 
            Type: controller                                   
            SCSI ID: deadbeaf1:0                               
            SCSI SN: beaf10                                    
            Size: 0 MB                                         
            Online: Yes                                        
            Removable media: No                                
            Backing store: No backing store                    
        LUN: 1                                                 
            Type: disk                                         
            SCSI ID: deadbeaf1:1                               
            SCSI SN: beaf11                                    
            Size: 1480476 MB                                   
            Online: Yes                                        
            Removable media: No                                
            Backing store: /dev/superthecus/backup             
    Account information:                                       
        backup                                                 
    ACL information:                                           
        192.168.111.173                                        
Target 2: iqn.2007-02.net.syneticon:superthecus.backup1        
    System information:                                        
        Driver: iscsi                                          
        State: ready                                           
    I_T nexus information:                                     
    LUN information:                                           
        LUN: 0                                                 
            Type: controller                                   
            SCSI ID: deadbeaf2:0
            SCSI SN: beaf20
            Size: 0 MB
            Online: Yes
            Removable media: No
            Backing store: No backing store
        LUN: 1
            Type: disk
            SCSI ID: deadbeaf2:1
            SCSI SN: beaf21
            Size: 3221 MB
            Online: Yes
            Removable media: No
            Backing store: /dev/superthecus/backup1
    Account information:
    ACL information:
        ALL
Target 3: iqn.2009-02.net.syneticon:superthecus.test
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 1
            Initiator: iqn.2006-08.net.syneticon:server.syn2
            Connection: 0
                IP Address: 192.168.4.52
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: deadbeaf3:0
            SCSI SN: beaf30
            Size: 0 MB
            Online: Yes
            Removable media: No
            Backing store: No backing store
        LUN: 1
            Type: disk
            SCSI ID: deadbeaf3:1
            SCSI SN: beaf31
            Size: 2147 MB
            Online: Yes
            Removable media: No
            Backing store: /dev/superthecus/test
    Account information:
    ACL information:
        ALL


> 2) you use slow network in this configuration, as you said before?

Yes.
Slow connection is just 5 kB/s in both directions.
It's easy to reproduce the problem this way.
Slow link is the third target above.


> 3) All your bug reports about this problem happened in this
> configuration? If not, please tell me about the other configuration.

In "real life" it happens under slightly different (more complex, harder to set up) conditions:
- tgtd uses DRBD resource as the block device (backing store)
- link is about 100 kB/s (writes; DRBD replication over a slow internet connection) and fast local HDD IO (reads)
- when DRBD exchanges bitmaps with the remote peer, it suspends IO for several seconds
- more targets configured, more initiators connected


-- 
Tomasz Chmielewski
http://wpkg.org
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