RAC Tests

[Former Member]

Hello,

I saw documentation for the RAC installation in SAP, however i can not find any list or suggestions for test the High Availability of RAC in a SAP enviroment.

Does anyone could advice ?

TAF is configured at the listener level as oficial sap-rac documentation, but i dont know how works with sap

Shall i expect that the sap transaction still working after an instance failed ?

Does the sap session still connected and the sap transaction will died ?

Best Regards & Thanks in advance,

sapcrosas

[Former Member]

Hello mho,

I dont understood about you mentioned

but SAP does not do it so far

[Former Member]

Hello mho,

I dont understood about you mentioned:

-

---

TAF has to be implemented on application (SAP) side, but SAP does not do it so far

As per configuring SAPNetware for RAC, TAF is configured

(FAILOVER_MODE =

(TYPE = SELECT)

(METHOD = BASIC)

do you mean that even if is configured TAF it doesnt work with SAP or im taking about another thing?

Regards & Thanks,

Sapcrosas

[Former Member]

do you mean that even if is configured TAF it doesnt work with SAP

Yes, that is what i meant, but I looks like I got that wrong. In my place we use a configuration with one oracle instance and one SAP instance per server. SAP is setup to connect to the local instance. In this special scenario TAF isn't helping a lot, because if the node dies, then the users connected to that SAP instance would need to reconnect anyway.

Sorry for mixing two different things up and causing confusion. At least I learnt something new now

If your workprocess was connected to the failing node, then your transaction fails as well. If you were on another node, then you live.

So this is not correct, with TAF the workprocess should be able to retry a current select statement. But you really should test that. You can try to use transaction SE16 and do a selection on a large table and shutdown abort the instance where the statement is running.

Regards, Michael

[Former Member]

Hello Michael,

Thanks for your clarifications

Perhaps should be good setup TAF in your enviroment

Does any one has a test in mind with SAP & RAC

Regards,

C

[Former Member]

Hi Michael

you stated

 then the users connected to that SAP instance would need to reconnect anyway 

This is not correct. The SAP instance and thus the connected user do not need to reconnect. If the SAP TAF has been implemented in the right way, then the users/SAP instance will be automatically reconnected to a surviving RAC instance

regards

Barthez

[Former Member]

Hi,

did you use the RAC for SAP white papers http://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/d149ec34-0d01-0010-4791-db4f1d864...

What do want to know about the tests?

Barthez

[jgleichmann]

Hi,

please keep in mind if you use RAC, you have only a HA of the instances not of the db, the db is everytime the same one. So in my opinion it´s not a complete HA solution, if your db crashes your HA of your instances won´t help you

If you are interesting in HA refer to physical data guard.

I don´t have any experience with RAC, so I don´t can answer your RAC questions.

Regards,

Jens

[Former Member]

@Jens: the db does not crash, only instances crash (<-- i hope this starts a discussion

So in my opinion it´s not a complete HA solution

The db consists of the data files, control files and redo logs. If you put them on a HA disk solution (mirrored to another site etc), then you will have a valid HA solution. Besides that RAC can be combined with data guard.

@sapcrosas: TAF has to be implemented on application (SAP) side, but SAP does not do it so far

Shall i expect that the sap transaction still working after an instance failed ?

If your workprocess was connected to the failing node, then your transaction fails as well. If you were on another node, then you live.

Regards, Michael

[jgleichmann]

hehe, you are right Michael, it was a false expression from me. If you have a physical or logical error on db side the 'normal' RAC concept won´t help you

Besides that RAC can be combined with data guard.

that's what I would like to address, because a 'normal' RAC which he mentioned above isn´t a valid HA solution

remote mirroring vs. data guard

Regards,

Jens