Subscribe

V-Series and LUN 0

Does anyone have experience with v-series appliances (not vfilers)? Chapter 6 in the planning guide states, 'Do not map LUN 0 to V-Series systems, even if LUN 0 is a storage LUN'. I just wanted to know why we're not supposed to map LUN 0 to the v-series? The guide doesn't go into any detail on this. I ask because I've already mapped LUN 0 and would like to know if something will break if I don't change things.

Cheers

Ian

Re: V-Series and LUN 0

In our implementation it just didn't show up as a LUN that we could use.  Though I think there were other oddities with it but I can't recall at this point.

I would echo the doc though, don't use LUN0 when presenting storage to the vseries...

Re: V-Series and LUN 0

LUN 0 is used by different array vendors for different things. EMC uses LUN 0 as a standard gatekeeper LUN. EMC CLARiiONs use LUN 0 as a virtual lun to check host connectivity, check zoning etc. This LUN may disappear after the checks are finished. If I remember right, Hitachi uses LUN 0 for special boot access. When a V-Series expects a LUN, it expects a LUN to overwrite and use for WAFL operations, so this may be the reason why they say not to use LUN 0...

my $0.02

cheers

Re: V-Series and LUN 0

Yes - that's all absolutely correct. Lun0 has special significance to many arrays - so best practice is to avoid using lun id 0.

Re: V-Series and LUN 0

LUN0 was used by arrays and often presented as an unsupported size to V-Series.  This LUN is often <1GB which is less than what we support.  On IBM arrays, LUN31 was often an issue for the same reason.  We are building in fixes to future releases of ONTAP.

Re: V-Series and LUN 0

I have a similar question with ONTAP 8.1.1.   We are currently running ONTAP 8.1.1 on a v3240 HA pair.   We are using 3rd party virtualization and someobody mapped a LUN with ID 0 from the EMC Clariion to the NetApp v3240.   The v3240 see's the LUN fine and we are currently using it in an aggregate.

We are in the process of reconfiguring the 3rd party array and would like to "unpresent" all 3rd party array LUN's.   Seeing this note about LUN 0 makes me wary of unpresenting LUN 0 from the EMC array to the NetApp.    Can I remove simply remove LUN 0 using the process outlined in the vSeries Maintenance guide or do I need to handle LUN 0 in a special manner?

Thanks,

-J

Re: V-Series and LUN 0

Starting in Data ONTAP 8.1, you can map LUN 0 to Data ONTAP if it is a storage type LUN.

Re: V-Series and LUN 0

For what it's worth, we had lun0 mapped and used for years in my old environment with no issues (set up this way by the PS guys, and by the time I saw the note not to use lun 0 it was too late).  This was a V3020 running various versions of ontap 6, 7 and 8.0 against HDS USP-V.  It also worked on a V3240 with ontap  8.0 against HDS VSP.  Never saw a problem.

Bill

Re: V-Series and LUN 0

I really appreciate the feedback!

We are also having no problems using LUN0 on our v3240.   We are just looking to unmap our Clariion based LUN0 from the v3240 and I see various notes in NetApp documents regarding special handling of LUN0 from 3rd party arrays.

Sounds like you had no problems.   Does that mean you also had no problems unmapping a 3rd party LUN with a host id of LUN0 from your v3020/v3240?

Re: V-Series and LUN 0

Hmmm, I don't think I ever tried!  As I recall, lun0 was used for aggr0/vol0, so pulling it was never really something I would have wanted.  I wouldn't think there would be an issue, but then then as you say the docs do have warnings.  Might be worth talking to support about.

Bill