Hi All,
I went through one of the documentation in SAP HANA Memory management .
http://www.saphana.com/servlet/JiveServlet/download/2299-2-12806/HANA_Memory_Usage_v2.pdf
This gave me a really good understanding about the Memory management of HANA . Queries for Used and Resident memory and comparison with Overview tab numbers
I had few questions , Which was almost answered in other discussed in one :
But i still have few questions about Resident and used memory
Used Memory : Code + Tables + DB Managment
Resident : what is the formula or content ?
What does this picture refers to ?
Infact the below statements are bit confusing
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When memory is required for table growth or for temporary computations, the SAP HANA code obtains it from the existing memory pool. When the pool cannot satisfy the request, the HANA memory manager will request and reserve more memory from the operating system. At this point, the virtual memory size of the HANA processes grows.
Once a temporary computation completes or a table is dropped, the freed memory is returned to the memory manager, who recycles it to its pool, usually without informing Linux6. Thus, from SAP HANA’s perspective, the amount of Used Memory shrinks, but the process’ virtual and resident sizes are not affected. This creates a situation where the Used Memory may even shrink to below the size of SAP HANA’s resident memory, which is perfectly normal.
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My doubt here is how in any given point of time used memory can go below the used memory , because resident memory is always loaded with what is there in used memory , When used memory itslef is less , what does resident contains extra .
Also how to make a relation with HANA used memory , Database Resident memory , Virtual memory .
In case of a memory issue , what should we check , Used memory of HANA OR resident memory of HANA ?
Thanks,
Razal