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how to calculate hana memory usage using view HOST_RESOURCE_UTILIZATION_STATISTICS

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Hi all,

I want to know the actual HANA memory usage to estimate how long HANA will last for us depending on the data growth. I used SQL "HANA_Resources_CPUAndMemory_History" in note 1969700. But the calculated result for memory usage is beyond our expect.  The sql result shows memory usage is more than 60% , but according to our statistic data the table size is only occupied 30% memory.

So I check the sql statement and found it takes field "USED_PHYSICAL_MEMORY" as the used memory(numerator ), but there is another field "INSTANCE_TOTAL_MEMORY_USED_SIZE" , the value of the latter is much smaller.

So I have two questions:


1. Why the memory usage got from sql is much bigger than the memory shows in Hana studio- Administration-Lanscape.?

2. If I want to know the actual used memory, I should choose which field in view HOST_RESOURCE_UTILIZATION_STATISTICS?


Hope anyone can help me.

Accepted Solutions (1)

Accepted Solutions (1)

lucas_oliveira
Advisor
Advisor
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Hi WeiFeng,

The used size x cs size ratio will not be 1:1. This is explained in the official documentation and discussed here a few times as far as I remember. Same applies for physical x used memory. So please look into the docs and scn discussions on that.

Question 1 can be answered with the documentation directly, so please refer to it.

Question 2 would be INSTANCE_TOTAL_MEMORY_USED_SIZE. per host basis.

Generally, for Memory utilization / peak /allocation I'd rely on query HANA_Memory_Overview_Rev90 from the same note you mentioned. Additionally, it gives you a nice idea of the biggest tables/allocators/area as a plus

There are quite a few HANA notes for sizing out there. Many of them will consider growth as well, so I believe it's a good start. I'd go for those first depending on what kind of application you're using (quicksizer / bw on hana / suite on hana). I believe all of those Notes are referred here:


1514966 - SAP HANA 1.0: Sizing SAP In-Memory Database


I hope that helps

BRs,

Lucas de Oliveira

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Hi  Lucas,

Thanks for your kindly reply. I have read the documents you provided and some discussions in SCN. For question one I still has some confuse. As I said before the memory usage I got from view HOST_RESOURCE_UTILIZATION_STATISTICS is more than 60%. I guess it is the memory usage in OS. It is much larger than the memory usage I got from Hana studio- Administration-Lanscape.  So why other processors in OS cost so many memory. In SAP document - SAP HANA Memory Usage and the Operating System,  it said

On a typical SAP HANA appliance, the resident memory part of the operating system and all other running programs usually does not exceed 2 GB. The rest of the memory is therefore dedicated for the use of SAP HANA.

Our example for one instance:

INSTANCE_TOTAL_MEMORY_ALLOCATED_SIZE: 1.48T

INSTANCE_TOTAL_MEMORY_USED_SIZE:  0.58T

USED_PHYSICAL_MEMORY: 1.27T

Please help to point out if I had mistakes.

Thank you!

lucas_oliveira
Advisor
Advisor
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Hi WeiFeng,

Why are you going for landscape to check memory overall consumption ? Thats going to give you a by host/service drilldown of memory allocated / used.

60% on what exactly? What are you comparing this to and why? What columns are you using for comparison?

Show the result of your query here and then clarify your questions. Clarify your HANA revision as well.

Thanks,

Lucas de Oliveira

Former Member
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USED_PHYSICAL_MEMORY is an operating system value that includes the SAP HANA allocated memory, not only the SAP HANA used memory. For the OS it is used, regardless whether it is only allocated or really used within SAP HANA.

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