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SAP ZAMM for AIX in LPAR envirnoment

Dec 20, 2017 at 03:24 PM

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Former Member

Environment: We have an LPAR which has 282 GB of RAM, in that LPAR we installed sap systems ECC, BW, XI, CRM, SRM, EP and MDM with one instance per each system. The DB is on separate LPAR.
PHYS_MEMSIZE for ECC is given 282 GB, for BW 112.3 GB, for SRM 512 MB and for CRM 512 MB.


Note: LPAR is a Host a on which virtual servers are installed and we have a dedicated virtual server for each sap system, SAP systems mentioned above.


OS: AIX.


DB: Oracle

SAP Kernel: 7.42


Question: We need to implement ZAMM, so request your inputs in maintaining PHYS_MEMSIZE parameter in this environment.

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5 Answers

Yogesh Patel
Dec 20, 2017 at 03:31 PM
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Hello

Please go through SAP note below for your referance.

2085980 - New features in memory management as of Kernel Release 7.40

If you set parameter PHYS_MEMSIZE SAP Kernel calculating rest of memory parameters considering assigned memory to PHYS_MEMSIZE.

Please let me know if you have any other question.

Thank you

Yogesh

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Isaias Freitas
Dec 21, 2017 at 11:15 AM
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Hello Narendra,

How much memory will be allocated for each system on that same LPAR depends on your own business needs related to each system.

Maybe the SAP Sizing website can help.

Regards,

Isaías

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Former Member Dec 21, 2017 at 09:25 AM
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Thank you Yogesh for your response. I have gone through this sapnote 2085980 before I have posted. My question is when LPAR has 282 GB of RAM and It accommodates multiple SAP systems, then how much RAM should be allocated to PHYS_MEMSIZE for all the SAP systems. Thank you in advance for your advise.

Thank You,

Narendra.

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Hello Narendra,

As Isaias Freitas mentioned in his answer if you have gone through sizing exercise you will get the right numbers for memory allocation otherwise it can effect system performance.

Thank you

Yogesh

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Matt Fraser
Dec 21, 2017 at 03:47 PM
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Narendra,

You shouldn't have PHYS_MEMSIZE exceed the actual physical memory in the server. You mention that your VM host has a total of 282 GB of RAM, and that you have 7 VM instances configured on that host. I'm not an expert on how to provision memory allocation for VM instances, but it seems unlikely to me you can provide the full RAM -- or more, if I understand you correctly -- to multiple instances on that host.

Regardless, if each SAP instance is getting its own VM server instance, and none of them share that instance with the DBMS, then probably you don't need to configure PHYS_MEMSIZE at all. Instead, just make sure you've appropriately provisioned the VMs; PHYS_MEMSIZE, if left unconfigured, will default to the amount of RAM detected in the VM, i.e. the amount you provision to that VM. And, as Yogesh mentions, almost all of the other memory and buffer parameters will auto-configure from that, so you likely don't need to set any at all.

One comment I will make is that the 742 kernel is now out of support. You should use at least the 745 kernel, and even better you should look at the 749 kernel. Not only are they in support, but they have improved zero-administration memory management features over 742.

Have a look at https://blogs.sap.com/2015/09/08/auto-tune-your-buffers-with-kernel-742/ (yes, shamelessly promoting my own (old) blog, and yes, when I wrote it 742 was the latest and greatest -- but what I wrote pretty much holds true, if not more so, for the later kernels).

Cheers,
Matt

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Reagan Benjamin
Dec 22, 2017 at 12:57 AM
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I will only look into the sizing numbers only when setting up a new landscape. If the systems are used for production activities then I will look into the memory usage statisctics and configure the memory parameters rather than wasting time with the sizing tool. Based on what you have written in your intial post it appears to me that you have SAP ECC, BW, XI, CRM, SRM, EP and MDM App servers running on a single LPAR with a total of 282 GB RAM. Correct me if I am wrong. If this is the case then I can very well say that this is badly designed SAP landscape. Java systems are sensitive to memory. Having both the stacks running on same partition will only create performance issues. If possible you separate systems on each partition with its set of CPU and memory. I am wondering why you have set only 512 MB for PHYS_MEMSIZE on SRM and CRM systems. If you have multiple instances running on the same host then you need to restrict the memory allocation for each instance using the parameter PHYS_MEMSIZE. To figure out how much memory should be set for PHYS_MEMSIZE on each instance, you should look into the total EM usage. For example if the EM/TOTAL_SIZE_MB parameter is set to 7 GB I would then set the PHYS_MEMSIZE in the range of 10 to 11 GB. Based on my knowledge an LPAR on a P-Series machine is a virtualized environment of a physical server with its own OS, CPU and Memory. What you have mentioned under so called "Note" is incorrect. If the SAP instances are running on separate LPAR's (with its own OS, CPU and Memory) then you should set the PHYS_MEMSIZE to the amount memory allocated for the partition.

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