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Restrictions on memory parameter em/initial_size_MB in SAP ECC 5.0


we recently upgrade ram memory from 12Gb to 24 GB on our SAP ECC 5.0 to solve performance issues.

We had some dumps related to memory issues and work processes gone in PRIV mode.

Now I would like to change some memory related parameters, particularly em/initial_size_MB.

These are the actual values:

em/initial_size_MB = 8192

em/blocksize_KB = 4096

Reading the description of the parameters in transaction RZ11, I read the following restrictions for em/initial_size_MB: The value must be smaller than/equal to (em/blocksize_KB * 2)

So it seems that to increase the first i have necesssarily to increase the second.

This is very strange, because the related SAP Note 146289 - Parameter Recommendations for 64-Bit and SAP Note 835474 - More than 32 GB extended memory - this restriction is not even mentioned. So can I ignore this restriction safely and set the parameters in this way?

em/initial_size_MB = 12288

em/blocksize_KB = 4096

Thanks in advance,



Hi Valerio,

According to note #146289 (Parameter Recommendations for 64-Bit SAP

Kernel) you can increase 'em/initial_size_MB' up to 32768 if the

parameter 'em/blocksize_KB' is set to 4096 according to note #182067.

In this case, em/blocksize_KB must bemust be increased, e.g. to 4096 (default for 4.6 64-bit systems). em/initial_size_MB up to 32768 is then possible."

'em/blocksize_KB' should not be increased to maximum amount unless you

plan 'em/initial_size_MB' to be greater than 16GB and so in this case

for performance reasons you should increase 'em/blocksize_KB'. After

this any warnings in RZ10 can be ignored about the maximum as the

kernel knows how to use the larger values.

So your findings are perfect and you can increase the em/initial_size_MB to 12GB, not a problem and if you still find the error "E:em/initial_size_MB greater than maximum 8196" in the system then you can refer to SAP Note 1154874 which tells to ignore the warning.

Hope it helps!!

Thank you,


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