This blog contains experience gained over the years of implementing (and de-implementing) large scale IT applications/software.

HowTo: Calculate SAP ASE HADR Replication Agent Buffer Pool Maximum Size

Scenario: In a SAP ASE HADR system, the primary ASE database log contains the following warning:
RepAgent(X): Autoscaling: Warning: The maximum configured buffer pool size:8 is less than the allocated buffer pool size:200. The maximum is set to 200“.

You would like to know what is a good value for buffer pool max size and how do you know we have enough memory assigned to the Rep Agent?

If we reference here: https://help.sap.com/viewer/075940003f1549159206fcc89d020515/16.0.3.8/en-US/fe0b1842bd1c1014858c88846330cc94.html
We can see that the “buffer pool” number is actually the number of buffers, which is also known as the “number of packages”.

If your current parameter values are as such:
“buffer pool maximum size” = 200
“stream buffer size” = 1572864 bytes (1.5MB)
“rep agent memory size” = 500MB

We can calculate the amount of memory needed for the Rep Agent like so:
max 200 packages x 1.5MB = 300MB of Rep Agent memory.

Now we know how to work forwards in the calculation, we can work backwards, starting with the Rep Agent memory:
300MB of Rep Agent memory / 1.5MB = 200 packages (buffer pool max size).


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