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 Post subject: LUN ID limitation?
PostPosted: Thu Apr 12, 2018 2:55 am 

Joined: Mon Mar 26, 2018 9:30 am
Posts: 15
hi @ all,

when i want to export a volume to a windows server (2012 R2) is there a limitation about the LUN IDs ?

I export a vol with lun id 5 no problem. if i want export the same vol to the same server and i export the vol with lun id 301 i can not see the vol on the server

thanks
kkw


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 Post subject: Re: LUN ID limitation?
PostPosted: Thu Apr 12, 2018 4:18 am 

Joined: Wed Nov 09, 2011 12:01 pm
Posts: 392
Most things support LUN ids in the 0-255 range I think, beyond that often requires tweaking HBA, driver, OS, array settings.
I've not had to go beyond 200 on most boxes, 3PAR think supports much higher if required but I'd check you're HBA BIOS settings to see if there's a scan beyond 255 option. Have also seen on older kit a need to see at least one LUN in a low range (maybe below 16) before it'll scan any higher.
Extended scanning will probably increase boot times too.


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 Post subject: Re: LUN ID limitation?
PostPosted: Thu Apr 12, 2018 4:44 am 

Joined: Tue Mar 29, 2016 9:32 pm
Posts: 136
KKW wrote:
hi @ all,

I export a vol with lun id 5 no problem. if i want export the same vol to the same server and i export the vol with lun id 301 i can not see the vol on the server



If you are presenting the same LUN to the host twice with different LUN IDs I would think the multipathing software would just treat the extra LUN as different paths to a volume it already knows about ... I've used that trick with other OSs not tried Windows though :-)

Plus as Ailean says .. lots of OSs stop counting after 255.


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 Post subject: Re: LUN ID limitation?
PostPosted: Thu Apr 12, 2018 8:54 am 

Joined: Mon Mar 26, 2018 9:30 am
Posts: 15
Thanks for the feedback and the explanation. I understood the topic.


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 Post subject: Re: LUN ID limitation?
PostPosted: Thu Apr 12, 2018 9:41 pm 
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Joined: Tue Aug 18, 2009 10:35 pm
Posts: 1328
Location: Dallas, Texas
As previously mentioned, LUN# 301 is too high, keep it under 254.

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Richard Siemers
The views and opinions expressed are my own and do not necessarily reflect those of my employer.


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