[Users] ovirt / 2 iscsi storage domains / same LUN IDs

[Alex Leonhardt]

Hi Ayal,

Thanks for that - I was thinking the same after I did some more testing 
last week - e.g. shared a image file from a different iscsi target and 
the same iscsi target, the lun on the "same target" changed, the one on 
the "other target" did again the same - so I figured it had something to 
do with tgtd.

Thanks for below, I was looking into those options to try next week :) ...

Thanks
Alex


On 03/03/2013 06:34 PM, Ayal Baron wrote:
>
> ----- Original Message -----
>>
>>
>>
>>
>> Hi there,
>>
>> I was doing some testing around ovirt and iscsi and found an issue
>> where as when you use "dd" to create "backing-stores" for iscsi and
>> you point ovirt to it to discover&  login, it thinks the LUN ID is
>> the same although the target is different and adds additional paths
>> to the config (automagically?) bringing down the iSCSI storage
>> domain.
> There is no question about the behaviour, it's not a bug, that is the way multipathing works (has nothing to do with oVirt).  The GUID of a LUN has to be unique.  multipathd seeing the same LUN ID across multiple targets assumes that it's the same LUN with multiple paths and that's how you get redundancy and load balancing.
> Why tgtd doesn't take care of this built in I could never grok, but what you need to do is edit your targets.conf and add the scsi_id and scsi_sn fields.
>
> Example:
> <target MasterBackup>
>       allow-in-use yes
> <backing-store /dev/vg0/MasterBackup>
>           lun 1
>           scsi_id MasterBackup
>           scsi_sn 444444444401
> </backing-store>
> </target>
>
>> See attached screenshot of what I got when trying to a "new iscsi san
>> storage domain" to ovirt. The Storage Domain is now down and I
>> cannot get rid of the config (???) how do I force it to logout of
>> the targets ??
>>
>>
>> Also, anyone know how to deal with the duplicate LUN ID issue ?
>>
>>
>> Thanks
>> Alex
>>
>>
>>
>>
>>
>> --
>>
>>
>>
>> | RHCE | Senior Systems Engineer | www.vcore.co |
>> | www.vsearchcloud.com |
>>
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