Hi experts, I am sizing an S1122 server for a refresh of a S922 with 128GB. The customer wanted to use the same amount of physical memory to cut cost although I proposed a server with 256GB of memory, as I heard from my TLS colleagues that the PowerVM Hypervisor and system firmware pre-allocate a substantial slice of physical RAM (about 10-15%) during installation, easily 20GB out of a 128GB Power10/11 server. They had experienced seeing servers with reserved memory doubled from 9GB to 18GB when upgrading firmware from eg. ML1030 to ML1060. Here's what I had feed into the System Planning Tool (SPT):
It shows that the hypervisor reserved memory is ~20GB out of the installed 128GB, giving a short fall of ~12.5GB (in red) as shown in the diagram above.
1. May I check why is the IBM Power S1122 consuming so much hypervisor reserved memory as compared to Power S922 servers ?
2. By using the SPT, am I showing the customer the correct way of how much reserved memory the server would consume?
3. According to my TLS colleagues, even you set "Dynamic I/O Drawer Attachment" to zero, you only can claimed a mere 2.75GB, is there anyway for us to reclaim back more reserved memory?
Your reply most appreciated...
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Thanks and Best Regards,
Shawn LEE
Systems Technical Specialist
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