is cluster possible?

[Vishu]

Hi Friends,

Three doubts. Need your valuable replies on it.

Is cluster possible in the below conditions and the most important is WHY?

1) Two different servers i.e. PA-RISC and integrity and same OS versions.

2) Two Same hardware with different OS versions (or if we have the same SG version, then also)

3) Two same hardware and same OS versions, but Different SG versions.

Thanks in advance

[smatador · Accepted solution]

Hi,
You have to read the releases notes of SG.
Look at this links for example
http://docs.hp.com/en/5971/SG-SGeRAC-SMS-EMSSupport.htm
http://docs.hp.com/en/T1905-90000/ch01s01.html#d0e209
http://docs.hp.com/en/T1905-90000/ch01s06.html
The answers depends of the release of your SG, your hardware, what OS your are considering etc.
HTH

[Matti_Kurkela]

1.) Yes, it's possible. We had one such cluster. It is useful if you e.g. want to increase the capacity of your current PA-RISC cluster by adding new Integrity nodes (because you can't get new PA-RISC servers any more, only used and factory-refurbished ones).

This allows you to upgrade your cluster to Integrity in easy steps, one node at a time (rolling upgrade): you don't have to build a completely new Integrity cluster to totally replace the existing PA-RISC cluster.

Of course it means your packaged software must be PA-RISC versions, if you want the package to be able to failover to the PA-RISC node: PA-RISC nodes will run them as usual, and Integrity nodes will automatically use the Aries emulator built in to every Integrity HP-UX system.

Once you have at least two Integrity nodes in your cluster, it becomes possible/useful to package native Integrity software.

(You *can* create SG packages with native Integrity software even if you have just one Integrity node, but as long as there is no failover node for it, the package is no more fault-tolerant than a stand-alone server.)

Serviceguard does not automatically recognize whether the application within the package is PA-RISC or Integrity, so you must configure the packages containing Integrity software to run on Integrity nodes only, otherwise SG may uselessly attempt to failover an Integrity package to a PA-RISC node, where it will obviously fail.

2.) Yes, but one Serviceguard version will usually cover only two consecutive OS versions, e.g. 11.11 + 11.23 or 11.23 + 11.31 can be done, but 11.11 + 11.31 is not possible.

This is not a recommended configuration for long-term operations, but possible and supported for rolling OS upgrades.

3.) Only for the duration of a rolling Serviceguard upgrade.

While there are two different versions of Serviceguard participating in the cluster, you cannot make any changes to the cluster configuration (= cmapplyconf will refuse to apply any changes). You can run and halt packages and nodes, but that's all.

You should read the chapter on software upgrades in the "Managing Serviceguard" manual. The book is available in http://docs.hp.com : go to High Availability -> Serviceguard, then pick the version of the book that is appropriate for your Serviceguard version.

The release notes will contain important information too, exactly as smatador wrote.

MK

[Vishu]

Thanks for the replies.

Rolling upgrades ??? you mean upgrading a SG or upgarding an OS ???

Any procedure to upgarde an SG version in both nodes while cluster is running??

[Sunny123_1]

Hi

I didn't think so. Refer the following document.

http://www.docs.hp.com/en/T1859-90048/apas01.html


Regards
Sunny

[likid0]

If you need to upgrade your service guard version, without shuting down the cluster you need to do a rolling upgrade.

Very quickly, it looks like this:

reallocate all the packages to node 1.
cmhalnode sg on node 2.
update sg version on node 2.
cmrunnode sg on node 2.
check everything is ok.
reallocate all the packages to node 2.
cmhalnode sg on node 1.
update sg version on node 1.
cmrunnode sg on node 1.
leave all the packages on there starting position.

there are a lot of ifs and buts with rolling upgrades, you have to check them out on the sg doc.