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Adding paths to active SCSI LUNs on XP256

Michael Simone
Frequent Advisor

Adding paths to active SCSI LUNs on XP256

I'm trying to do something I thought was simple, but now HP has made me think it might not be.

I have an N4000 (MPE7.0) connected to my XP256 through 3 SCSI ports (1J,1K,2J), 8 LUNs per port. This is my production box, so these ports/LUNs are active.

I'm implementing Cluster/iX with HP's help, and need to create a second set of paths to these same LUNs for the standby server, but on different SCSI ports (1M,2L,2M). The standby server will be configured in such a way as to not disturb the active LUNs (HP is onsite to do this part).

Question is, can I add new paths to these LUNs in Define (Offline) without disturbing the current active use of those LUNs? I would think so, because the ports I'm adding paths to (1M,2L,2M) are NOT active, and my understanding is it's the PORT that has to be inactive, not the whole channel. And I'm just adding a path, I'm not actually doing anything to the disks or the data in those LUNs. Right?

If anyone has done this before, I'd sure appreciate some guidance. HP Stress-Free is throwing out vague concerns about MPE and the XP, and I don't see how MPE even plays into this. But I want to be safe.

Vincent Fleming
Honored Contributor

Re: Adding paths to active SCSI LUNs on XP256

You've got it right.

Adding paths to LUNs will not change the data on the LUNs.

Offline mode will require that you have no traffic on the ports being modified (1M, 2L, 2M), and works best when the cable is not connected to the port (thereby preventing any traffic). You can add LUNs to a port in Online mode as well. (Only deleting LUNs from a port must be done in Offline mode)

I'm sure that the people at Stress Free are just concerned with the second MPE system. The frame operation of assigning the LUNs to the port is a no-brainer.

Don't forget to set the host mode behavior! Something like that could cause your second MPE system to hose the data on the LUNs should it get a hold of them. Be sure to go over the settings with Stree Free.

Good luck!

Good luck!
No matter where you go, there you are.
Insu Kim
Honored Contributor

Re: Adding paths to active SCSI LUNs on XP256

There're two modes, offline and online on the LUN configuration manager.
Offline means that there should be no IOs on the ports that are being modified.
On the other hand, in the online mode, you can only add new paths.
You can't delete paths there.

I have no experience with MPE but on HP-UX, adding a second path to a LUN is not a problem and doesn't disturb the ative LUNs configurd at all.
Never say "no" first.