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Title
Partial Memory and CPU reservation issues on SQL PI environment (Infobright) -
Description
Why are total Memory and CPU reservations required for SQL PI Environment?
Why are partial CPU and memory reservations insufficient for SQL PI?
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Cause
A reservation reserves up to the amount indicated - dedicated to that VM. So if you had a VM with 12 GB assigned but reserved only 4 GB, then the hypervisor would dedicate that 4 and anything over that would be utilized as needed by the VM.
Setting the reserve gives the VM it's total assigned memory and reserves it all. So if VM was assigned 12 GB of memory it would reserve all 12 GB so that no other VM can use that memory even under contention
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Resolution
The Infobright based version of SQL Performance Investigator (SQL PI) is out of support and has been replaced with a SQL Server based version of the PI repository in the 5.9.5.20 and higher releases of the database cartridges. Please upgrade the database cartridges to the most current release for continued full support of the product.
According to the Foglight for Databases deployment guide, the following resources must be allocated and reserved to monitor 1-50 instances with SQL PI.
- 4 Cores (4 x 2.4Ghz)
- 10 GB of RAM
If the Virtual Machine has a higher number of CPUs or Memory allocated (e.g. 12 GB RAM), then the entire 12 GB of memory configured in the virtual machine OS needs to be reserved so that the VM reservation matches the OS in a 1 to 1 ratio. This can easily be accommodated using the "reserve all guest memory" checkbox.
There is no way at the OS level to reserve certain memory to exclusively run for some processes or to set a priority for specific processes.
The amount that must be committed must be equal to the full OS setting in the Virtual Machine (OS + all applications + VM overhead).
