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How to remove an in use LDEV on the XP1024?

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Chad Sellars
Advisor

How to remove an in use LDEV on the XP1024?

I would like to remove a LUN that has some traffic. This traffic could be inexplicable traffic from a dismounted volume or it could be because the volume cannot be completely dismounted due to the OS. In any case, the LDEV cannot be removed from the host group. The XP returns an LDEV busy message and throws me in the penalty box for 5 minutes.
Now, the only workaround I know is to disable one HBA, pull the ldev from the host group, renable the HBA, disable the other HBA and pull the LDEV from the other host group.

This is just too scary for me to do on our big systems. Is there a command line way to do this on the XP?
Is there a /force option?

Thanks in advance
If it is about storage, I am interested.
6 REPLIES
Peter Mattei
Honored Contributor

Re: How to remove an in use LDEV on the XP1024?

I suggest you call HP and open a call. You will then be assisted either on the phone or locally!
It is much too dangerous to use force commands just like that!

Cheers
XP-Pete
I love storage
Chad Sellars
Advisor

Re: How to remove an in use LDEV on the XP1024?

Using some type of force command to remove an LDEV would not really be that dangerous. All of our hosts are dual pathed. I would like to remove the LDEV on one HBA, then run a rescan and verify that the correct LUN was removed. Since the hosts are dual pathed, even if the wrong LUN was removed, the host would not be impacted.

With VMWare, we have many common LUSEs shared by many systems. VMWare cannot unmount these LUNs like HPUX. We are being constantly asked to add and remove the LUSEs from these systems. Removing LUNs will become an increasingly common activity as the VMWare install base continues to grow.

So, yes I guess I will place a call if no answer is forthcoming here.

If it is about storage, I am interested.
Nigel Poulton
Respected Contributor
Solution

Re: How to remove an in use LDEV on the XP1024?

Chad,

I must side with Peter on this really..... but if you're sure your OK to go ahead and try yourself then the following might be helpful....

If there is any I/O going to the LUN you are trying to release, the XP will not allow you release the LU path and, like you say, will put you in the penalty box for a minute or two while it backs out of the release operation. The only way I know of to get around this is to make sure that the LUN is unmounted etc and TOTALLY unmapped on your HBA. I had a few problems in the past with Emulex HBAs and auto-mapping of LUNs. Auto-mapping LUNs is a SAN administrators nightmare in my opinion.

Failing that you may have to pull the cable. Im not aware of any system options that can be set on the XP that can be set to override this. Ive had this problem several times in the past with HDS badged kit and never got a satisfactory solution.

Some of the other things we tried were resting the affected CHIP port, sending multiple SCSI resets to the CHIP port, checking for SCSI-3 persistent reserves..... Ive had varying success with these techniques in the past.

Often Ive had to fail back (no pun intended) to pulling the cable.

Hope this helps.

Nigel
Talk about the XP and EVA @ http://blog.nigelpoulton.com
Shathishkannan
Occasional Advisor

Re: How to remove an in use LDEV on the XP1024?

Hi Chad,

There are some options which you can try.

1) Remove the LUN from the VG and then try to deallocate the LUN.

2) Disable the switch port on A side and deallocate on XP. Then disable the switch port on B side and then deallocate on XP by enabling the A side Switch port.
sivam
Advisor

Re: How to remove an in use LDEV on the XP1024?

Hi Kannan,

You are right. But as its VMWARE, Sellars has to be care full in noting down the cu:ldev & LUN numbers for all the hostgroups.

Force option is always adviasable after consulting with the HP.

If you are confident in getting done with force option, do the dealloction in single path, if its successful u can do in the other path.

sivam
Chad Sellars
Advisor

Re: How to remove an in use LDEV on the XP1024?

I will continue to use the port disable method
If it is about storage, I am interested.