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Remove LUN 0 on VA7400

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Carlos Munoz Lopez
Frequent Advisor

Remove LUN 0 on VA7400

Hi, we have two VA7400. Via Command View, our provider configured LUN 0 = 360 GB, it contains a volume group that we needed to remove in order to free that space. Now we need to reduce this LUN as well.

When trying to remove it, we got a warning that the array may be unavailable if we proceed. So, we checked previous answers from this forum regarding similar situations. We found out that LUN 0 is used by the VA management software and its size should be 10 MB.

Is that correct? How can we reduce this LUN from 360 GB to 10 MB?

I'd appreciate your help. Thanks
Steven E. Protter
Exalted Contributor

Re: Remove LUN 0 on VA7400

There is an issue with many disk arrays and HP-UX. If you don't have a Lun 0 assigned, the disk array itself is mis detected as a LUN. Of course since its not a disk EMS thinks there is a bad disk.

Remove all the data from the LUN. Make sure its backed up of course. Then use the lvreduce command to reduce the logical volume from 360 GB to 10 MB.

Steven E Protter
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Sridhar Bhaskarla
Honored Contributor

Re: Remove LUN 0 on VA7400


All you have to do is remove the VG and free up the LUN. Make sure that LUN is not active on the system by running the command "pvdisplay /dev/dsk/cxt0d0".

Then using VA management software, reduce it to 10 MB. Run 'ioscan -f' on the system and ensure that the size is reduced.

You may be disappointed if you fail, but you are doomed if you don't try
Carlos Munoz Lopez
Frequent Advisor

Re: Remove LUN 0 on VA7400

I already removed the VG and the PV. All data was backed up, so the LUN is free. I attach a file in which you can see the LUN distribution in the array.

Is there a way of reducing the LUN 0 size from 360GB to 10MB??

Re: Remove LUN 0 on VA7400


there is no way if reducing it. The only thing You can do is to delete it and make a new LUN0 with size of 10MB. I suggest having the serial cable for the VA ready and connected, in case Your CV software loses mgmt access after lun0 deletion. Then You can always use terminal access through serial port and put a command
cfg -L 0 -c 10M (hope the syntax is correct, haven't workd with the VA for quite a time...).
By deleting LUN0, You can lose MGMT access to the array (for VC software), and if You do not run ioscan while the LUN0 is deleted, other LUNs should be fine.
Bharat Katkar
Honored Contributor

Re: Remove LUN 0 on VA7400

LUN is at physical level and LV is at logical level. LV's are created on LUN.

LUN's are not flexible as LV's and hence they can't be reduced or increased.

You have to delete it and recreate.

Hope that helps.
You need to know a lot to actually know how little you know
Emilio Brusa
Frequent Advisor

Re: Remove LUN 0 on VA7400

Hi Carlos,

Armcfg is for create and delete Luns.
You need delete the Lun armcfg -L (lun) -d array-id and then recreate the Lun.
armcfg -L (lun) -a 10 -g (groupId) arrayID


Roger Buckthal_2
Frequent Advisor

Re: Remove LUN 0 on VA7400

Don't worry about deleting LUN 0. Command View will work without issue. 1) Command View -- a discover will find any usable LUN on the VA to use for managment. The VA does not map the managment commands to the logical address space of LUN 0 (or any LUN), but uses the mode pages of the LUN. So, LUN 0 is available for storage, just like any other LUN. 2) If no LUNs exisit on a VA, the VA will present a 'fake' LUN 0 so CV can manage the array.

The 10MB LUN 0 remendation is for shared environments that might include Windows. LUN 0 must be present for Windows to discover the array.
Carlos Munoz Lopez
Frequent Advisor

Re: Remove LUN 0 on VA7400

Thanks for all your recommendations. It really helped me a lot.