Considerations while upgrading AIX with SDDPCM installed

Considerations while upgrading AIX with SDDPCM installed

SDDPCM (Subsystem Device Driver Path Control Module) is the multi-pathing plug-in for AIX 5.3 and 6.1.

Customers who use IBM SVC, DS6000, DS8000 and/or ESS800 use this package to allow the operating system to handle multiple paths from OS to storage.
When you are upgrading AIX with SDDPCM installed, don’t forget to plan for SDDPCM too.
1) Planning an upgrade from AIX 5.3 to 6.1Before the AIX OS is upgraded, SDDPCM must be uninstalled and then reinstalled after the upgrade. There are cases when the host attachment script must also be uninstalled and reinstalled. This is explained in the SDD Users Guide found here:

2) Already upgraded AIX to 6.1 but still using AIX 5.3 version of SDDPCM?

You may need help from IBM before you can upgrade your SDDPCM to the AIX 6.1 version. This will come in the form of some special scripts.

3) General SDDPCM maintenance

There are quite a few SDDPCM flashes out there right now. You need to check these out and ensure you are not exposed to the issues that are corrected by later versions of SDDPCM. Check out the flashes listed here (or read my previous blog entry):

http://www-01.ibm.com/support/search.wss?rs=540&tc=ST52G7&dc=D600&dtm

What about SDD (Subsystem Device Driver) for AIX?
Prior to AIX 5.2 FP5, AIX did not offer native multi-pathing (MPIO). This meant that each hardware vendor had to offer their own third-party software to handle multiple paths. To achieve this with the ESS (Shark), IBM released a product called DPO (Data Path Optimiser). This product became SDD and was made available for a wide variety of operating systems.

When AIX offered MPIO, IBM then also offered a vendor plug-in (Path Contol Module) for native AIX MPIO which IBM called SDDPCM. This means you have two choices with AIX: SDD or SDDPCM. If your considering which is best, SDDPCM is my preference. This is because it is native to the operating system and also better supports the possibility of co-existence of multiple PCMs. Note that migrating from SDD to SDDPCM is not supported by the VIOS at this time, so if your running VIOS you will need to stay put for now.