Memory properties in Analysis Service

Preallocate
It will allocated specified amount of memory to analysis service.By specifying preallocate Analysis Service uses large memory pages and we can not swap this to page file. It can give better performance to Analysis Service.

So we have to be cautious and also count required amount of memory to other applications before assigning values to it.Its ideal we should keep at least 20% of memory to system.
Service account for analysis service must have lock pages in memory privilege.



TotalMemoryLimit
If value is set to between 0 and 100 its counted as percentage else if its greater than 100 then its count as absolute value in bytes.
It had default value of 80%

LowMemoryLimit
If value is set to between 0 and 100 its counted as percentage else if its greater than 100 then its count as absolute value in bytes.
It has default value of 75%.

if server cross this limits it experience memory pressure. Depending on requirement of memory server feels various levels of pressure.It will start cleaner thread to clean memory depending upon pressure on the server

Levels of Memory Pressure
  • When memory is in the specified range of TotalMemoryLimit and LowMemoryLimit there will no pressure
  • When memory between LowMemoryLimit and TotalMemoryLimit cleaner will begin to clean memory. It will clean data from cache which is less used compare to highly used cache data
  • If memory is greater than TotalMemoryLimit property, cleaner thread will clean the memory upto TotalMemoryLimit. If it can not release memory , it will try to cancel active requests. At this time we will feel various problem with analysis service related to performance.

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