In-memory computing is a fascinating technology – as long as the DB server memory doesn’t collapse with Hana data. If this happens, users can only hope and pray. It can take hours before the SAP system, SoH or S/4, reboots. The solution to this problem is supposed to be Intel Optane memory (Persistent Memory).
R/3 versus Hana
The first R/3 installation that I worked with operated on IBM RS/6000 with AIX and an Oracle database. Data was stored on external hard drives.
One time, the hard drives’ power supply was interrupted while the AIX server continued operating. This means that R/3 was technically still operating – but doing anything productive with it became impossible.
Once we restored the power supply to the hard drives, Oracle needed about fifteen minutes to automatically reorganize everything. After that, we continued business as usual.
A Hana database with six TB main memory would need at least an hour to reboot.
Intel Optane can help
With Intel Persistent Memory, Siemens IT experts were able to reboot in one hour and forty minutes. The ratio of DRAM to Persistent Memory was 4 to 1. The goal should be system configurations with equal parts DRAM and Optane.
Of course, DRAM is faster. Persistent Memory is a little slower, but more cost-efficient and more secure. That’s because data is encrypted in the chips. Technicians therefore need to find a balance between speed, price, performance and security.
SAP customer Evonik conducted a test with Optane and DRAM. Hana’s reboot time was reduced by factor twelve.
Nobody knows yet if this combination of DRAM and Optane will ever reach operational excellence. What we do know, however, is that Intel Optane Persistent Memory is a unique way to combine cost-efficient memory with persistent data storage which Hana as in-memory database can benefit from.