different allocation of sga sizes between primary and standby

[Ricky_4]

Hi All,

We are implementing Oracle clustering using MC Service Guard. Please assist us on the scenario that puzzle us. Here are scenario:

The primary server has 4 Gb of physical memory while the standby server has only 3 GB. And only instance is going to cluster. If Oracle instance is running in primary server, SGA size allocated is 2.5 Gb. Then, if it will failover in standby server SGA size allocated is 2 GB since standby has lower memory. We are puzzling how could we achieve this in MC Service Guard.


Hoping for you assistance.

Regards,

Adriatico

[Steven E. Protter · Accepted solution]

I'd achieve this in one of several ways

Simple approach would be to locate the init.ora file on local disk so when the package fails over to node 2 the smaller sga loads.
I'm sure the package startup script could also detect the hostname and run a different init.ora as well

The trick is to run the database off a different init.ora if you really need a different sga.

SEP

[Hein van den Heuvel]

As SEP writes, you'll need to present oracle with node specific initXXX.ora files.

Your choice at to how. A service guard script, a node specific directory, a magic softlink.. whatever.

But as you go there I would recommend a setup with a node-specific initXXX.ora file with a minimum number of parameters which are truly node specific. For example: db_buffers, pga_aggregate_target, sort...

Then after those 4 or 5 lines chain onward to the general/common setting for your enironment using a line like:

ifile = /ORACLE_HOME/dbs/initXXX_common.ora

hth,
Hein.

[Hamdy Al-Sebaey]

Adriatico,

I think there're two options:
From my point of view the difference in memory between the two nodes are not so high, so you can leave the situation as it's, it depends on if there is another application on the secondary server 're running or not.
In the init.ora you can change SGA to what ever you like, at the same time you can leave it as it's and create new swap area for critical situation if oracle is goning to use more memory then you 've swap .
Regards,
Hamdy

[Hamdy Al-Sebaey]

Adriatico,

I think there're two options:
From my point of view the difference in memory between the two nodes are not so high, so you can leave the situation as it's, it depends on if there is another application on the secondary server 're running or not.
In the init.ora you can change SGA to what ever you like, at the same time you can leave it as it's and create new swap area for critical situation if oracle is goning to use more memory then you 've swap .
Regards,
Hamdy