Simple sizing with PMEM
Your in-house SAP Basis Administrators or your Systems Integrator(SI) is able to answer these 2 questions for you
- How big is your SAP HANA database now(in GB or TB) now - Stored in PMEM
- What is the Working Memory / Scratch Pad size now? - Stored in DRAM
- 3 year growth in terms of # of users or DB size - Growth Factor
Eg. 10% is 0.10, 25% is 0.25, 50% is 0.50
Use the formula below to figure out the ratio of DRAM: PMEM
DRAM : PMEM = (DRAM + DRAM * Growth Factor) : (PMEM + PMEM * Growth Factor)
Sizing Suite on HANA System
SAP Note 2786237 has 2 SQL files attached and run this script in your production system and they usually take < 5 seconds to run on your SQL
Do not run the SQL script immediately after a HANA downtime which does not capture the peak DRAM metric properly.
As a rule of thumb most SAP HANA transactional systems usually fit in the 1:2(DRAM:PMEM) ratio & HANA Analytical systems like SAP BW usually fit in a 1:1(DRAM:PMEM) ratio.
For Non Production systems like Dev / Sandbox / Training higher ratios of 1:4 are possible.
BW ON HANA Sizing Deployment with PMEM
Below is the sample output of the SQL which we had run for a Customer running BW on HANA on a 4 + 1 scale out system today.
Analyzing SQL Output
The above script indicates that DRAM:PMEM ratio is 1:2 and that the node size can go up from 1 TB(current system) to 9 TB / Node. In this case the customer migrated from Scale Out to Scale Up architecture for their SAP BW on HANA landscape.
Benefits with PMEM
Lesser IT Headcount to Manage / Patch and Upgrade 6 Scale Up Nodes vs. 15 Scale Out Nodes. Able to encrypt data in memory using native 256 AES encryption PMEM DIMM Encryption
For an accurate sizing provide the below information to your OEM / Cloud Service Provider
- # of Environments Eg. Dev / QA / Production / Training
- Enterprise Storage Refresh strategy
- RTO / RPO requirements
- Planned Upgrades for next year / current year
- Non Production systems refresh strategy
Krishna Yalamanchi is a Technical Solutions Specialist at Intel in the Memory Solutions Product Group. He focuses on enabling Intel Optane persistent memory solutions with Hyperscalers, Global System Integrators (GSIs) and OEMs.