RAC database Migration

Question

Hi Experts,
I need some advice related to the Migration of RAC database, we have to migrate several RAC & Single-Instance databases from existing HP Itanium servers to Superdome2.
Initially I thought of going with "addnode" for new Servers as additional Nodes to the existing RAC database then remove old Nodes for RAC databases migration, but there are some limitations in our evironment,
1. There are no free IP addresses available to assign to new nodes from the existing IP segment.
The IP Range (1 - 255) is divided into into several small segments of 16 IPs in each segment, and the segment in which the existing 2Node RAC DB is completely occupied and there is no free IP Available.
If the new Node have IPs addresses from different segment in the same Subnet(IP Range) can it be added to the existing cluster?
and if we cannot find any IP in that Subnet then can the nodes with the IPs from other Subnet be added to the Existing Cluster?
2. To add a node to the existing RAC cluster, the new node should be exactly same, OS version, OS Patches...
Our existing rx Itanium servers have "*HP-UX 11.31 Mission Critical Operating Environment*" for One 2 Node RAC Cluster and "*HP-UX 11.31 Enterprise Operating Environment*" for for another 2 Node RAC Cluster, but the HP Superdome 2 will have the Latest "*HP-UX 11.31 Data Center Operating Environment*"
Can we proceed if there are some diferrences in OS patches...?
Please see the Existing Environment Details below:*
Prod 1 DB *2 Node RAC Cluster* :
Hardware: rx 8640 Itanium Server
OS: HP-UX 11.31 v3 Mission Critical Operating Environment
DB Version: Oracle 10.2.0.2
Prod 2 DB *2 Node RAC Cluster*:
Hardware: rx 8640 Itanium Server
OS: HP-UX 11.31 v3 Enterprise Operating Environment
DB Version: Oracle 11.2.0.1 (2 Node RAC)
Prod 3 DB *2 Node RAC Cluster*:
Hardware: rx 6600 Itanium Server
OS: HP-UX 11.31 v3 Enterprise Operating Environment
DB Version: Oracle 11.1.0.6.0 (2 Node RAC)
TARGET DB Environment for All the Databases will be;*
Hardware: HP SUperdome 2
OS: HP-UX 11.31Data Center Operating Environment
DB Version: Oracle 11.2.0.3 (2 Node RAC)
Also, all the 3 RAC databases are in Extended/Stretch RAC Cluster configuration and the new Superdome Env will also be in Extended RAC Cluster Configuration.
Kindly advice what strategy should I follow for the Migration, waiting for your kind reply.
Any help will be highly appreciated.
Thanks in Advance.

Answer 1

I am struck by your post with a couple of thoughts.
1. Even though high availability appears to be something you are willing to invest substantial money in obtaining ... no one think patching important.
2. Even though you've spent a substantial sum of money on hardware and software ... no one thinks networking important enough to address the lack of appropriate network infrastructure.
Personally: I'd advise refusing to do the work until management makes the very small investment necessary to doing it correctly.