Powerpath can't see paths when moving between SANs

Question

We have two SANs, one a CX3 and one a CX4.  The CX3 is going out of warranty, so we are transferring all data from the CX3 to the CX4 and as SANCopy isn't available to us, we are copying the data through the server as shown in the attached image. So, originally both HBA1 and HBA2 are connected to the CX3 SAN and working fine.  To start copying the data, we connect the HBA2 to CX4 SAN switch, create the LUNs, Storage Groups and Zone everything on the CX4 SAN and then reboot.  At this point, Powerpath can only see the path of the old HBA1 -> CX3 SAN connection and not the new HBA2 -> CX4 SAN.  So we then try and uninstall Powerpath, reboot and suddenly the paths for both connections appear which is what we want, but obviously they are not managed by Powerpath so we re-install Powerpath and reboot the server again and again, we only have the old connection to CX3 and not the new connection to CX4.  How do we make sure that the new connection is consistantly seen by Powerpath?  What am I missing? All help greatfully received. John

Tandok · Answer

If its Windows server, the failover mode should be 1 or 4, preferrably 4. Knowing the OS would help determining the required Failover mode Also check the initator type, again would be based on you OS.

dynamox · Answer

what version of PowerPath, OS, failover mode on CX4 ?

btst · Answer

Apologies for missing out the main bit of information. It is indeed a Windows Server, Windows 2003 Enterprise with SP2 to be precise. We're on version 5 of Powerpath. This will sound very basic, but is failover mode set in Unisphere?

Thanks and Regards

John

dynamox · Answer

Yes, failover is set in Unisphere. If you look in Connectivity Status (flare 31), click on the initiator and select info.

btst · Answer

dynamox

We found that two paths were set to 0 and two to 4. So, if we set them both to 4 and re-install Powerpath (presumably the lastest version?) do you think Powerpath will start managing the paths correctly again?

Regards

John

dynamox · Answer

PowerPath should manage it just fine. I presume you have presented some storage from CX4 , until you present any storage from CX4, PowerPath will not show any connectivity to that array.

btst · Answer

There is storage presented to the server, the OS recognises it, but Powerpath doesn't.  In fact it's running now with Powerpath removed, so we don't have the path redundancy, but we have got a wroking system.  We'll try that on another test box to repluicate all of the issues we had with the live server.

Maliboo74 · Answer

Once you change the failover mode to 4 for all initiators, you can reinstall powerpath and reboot. A reboot is a must.

The Navi/Uni agent is necessary to automatically register the host on the array. If you choose to use the agent you will no longer have to manually register the initiators on the array. The agent isn't required, but it's nice to have.

btst · Answer

One other query, should we be running Naviagent/Uniagent on the servers as well?  We've never used this before on any of our other servers, but reading some background info, we appear to need this?

PowerPath

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