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online lun addition

galenr
Advisor

online lun addition

Hey Gang-
I was trying to add luns online with HPUX 10.20 and could not. Had to
unmount file systems first then was able to add the lun. When tried on HPUX 11.0
this worked. Any comments on why it did not work with 10.20?

This was with an Hitachi 9900 disk array
5 REPLIES
A. Clay Stephenson
Acclaimed Contributor

Re: online lun addition

I find this very hard to believe. You see the LVM commands know absolutely nothing about filesystems - they couldn't care less if a filesystem is mounted or unmounted. This is true in 10.20 and 11x. I am more inclined to believe that you somehow missed a step or mistyped a command.
If it ain't broke, I can fix that.
Steven Mertens
Trusted Contributor

Re: online lun addition

hi,

Do you mean add a new disk to an existing
volumegroup ? Or to extend a logical volume ?
Do you have online JFS ?
I thought adding a new disk to a vg can
online also on 10.20.

regards
Steven
A. Clay Stephenson
Acclaimed Contributor

Re: online lun addition

I have one possible guess and I will preface this by saying that I have no experience with your array. Arrays typically have some sort of
host -> LUN assignment table to prevent multiple hosts from accessing the same LUN. It is just possible that your 11.0 box had already reserved these LUN's and when the 10.20 box tried to access these LUN's; they already appeared to be reserved.

This still does not explain why unmounting the filesystems allowed it to work. Filesystems are at a much higher level of abstraction than should apply in this case.
If it ain't broke, I can fix that.
William Shaw
Frequent Advisor

Re: online lun addition

It looks like the original question was about assigning LUNs to a storage port on the HDS 9900 while other LUNs on that port were mounted at the HP host. The HDS array has 2 modes for doing such an operation, online or offline. Online means LUNs can be added or removed while other LUNs on the same port are being access, or are online. Offline mode means no host access to the port in question. Anyway, using 'online' mode, you should be able to add LUNs to the array port, even while other LUNs on the same port are currently mounted at the host. If you are still having problems you should contact the HDS technical support center.

Regarss, Bil
Vincent Fleming
Honored Contributor

Re: online lun addition

I think Bill's got it here... Offline mode prevents you from changing the port while I/O (or any FC traffic) is active on the port. It will actually issue an error message and fail the operation if it sees any traffic on the port.

Online mode will allow LUN additions even if there is I/O on the port... but not deletions. Deletions can only be made if offline mode.

It sounds like our friend here is/was trying to use offline mode to add the LUN. Online mode should work.

Vince
No matter where you go, there you are.