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BW HANA Sizing - Results interpretation /SDF/HANA_BW_SIZING

FOA
Advisor
Advisor
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How should the results of the report /SDF/HANA_BW_SIZING be interpreted? is the recommended physical memory per node the final "HANA DB size" also displayed in the Readiness check report? It is very confusing as the sum of the memory 838 GB + data 1271 GB + log 512 GB disk size, is not equal to the recommended physical memory per node (1536 GB). 

Thanks for any clarification.

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Answers (2)

RolandKramer
Active Contributor
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Hello @FOA 
as you can see, the sizing Report shows that the System can hold comfortably in a 2 TB Node, as you shoud try to avoid to split into several nodes.

once the system grows regulary, try to consider to use Dynamic Tiering or nearline storage (NLS) as alternative for the historical data to keep the main memory in balance.

See also SAP BW NLS Solution and why SAP BW/4HANA?

best regards Roland SAP first-guidance
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FOA
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Advisor
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Hi Roland, thanks for your notes. I would be curios to know your point of view on what is stated in the document SAPBW4HANA_Sizing_V2.7.pdf, in note 2296290. Page 36:

1. The size of the data files will be approximately as large as the overall memory requirement.

2. Small systems (< 512 GB) require half the memory size for log files. For all other systems a
total of 512 GB for log files should be enough.

3. For executables, dumps, exports, etc. we recommend reserving at least 2x-3x the total
memory requirement.

Which in my example would be:
1. 838 Memory requirement + 838 for data = 1676
2. 1676 + 512 = 2188
3. 2188 + (838 x 2) = 3864,

Which would leads to a Hana DB tier of at least XL (3072 GB). Meaning once size bigger than the recommendation of 2 TB. Would you agree that the recommended physical memory of the report is not sufficient and the above needs to be considered? Or not at all?

mamartins
Active Contributor
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You cannot sum the memory (RAM) size with the disk sizes, because they serve different purposes!

Please look onto the PDF attached to the note mentioned on the report to help you read the results. Some notes:

  • The memory requirements include space for the tables, indexes (where applicable), and space for temporary database objects (e.g. intermediate query results).
  • Minimum vs. Recommended: HANA prefers a set of nodes with less memory over fewer nodes with more memory for cost effectiveness / flexibility reasons. Minimum memory amount is determined by requirements for coordinator node. For scale-out landscapes with more than 8 nodes the next larger server configuration is used (if available).
FOA
Advisor
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Thanks for your reply. I understand it shouldnt be added and I read the notes and pdfs before posting my question. However none of the guides provides the answer to this question: which is then the recommended BW/4HANA DB Size after the output of that result? Lets set aside for the moment the future growth and keep it for one node.
mamartins
Active Contributor
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Considering the recommended values, it will be:

  • Memory (RAM):       3 x 838 GB
  • Disk size for DATA:  3 x 1271 GB
  • Disk size for LOGS:  3 x 512GB