How to limit the HANA minimum allocation memory .

[Former Member]

hello all ,

we all know the global_allocation_limit default value is 0 , it means 90% of the physical memory ,
but How can limit the minimum of allocation memory ?

I set the parameter global_allocation_limit value to 2G(2048M) of all host , see the following snapshot ,It can not take effect.seems can not less then 13G, but if I set the value to 20G(20480M) , it will work well ,

-- set the global_allocation_limit=2048
hdbsql=> select round(allocation_limit/1024/1024,2) allocation_limit from m_host_resource_utilization;
| ALLOCATION_LIMIT                       |
| -------------------------------------- |
|                               13605.15 |

-- set the global_allocation_limit=20480

> select round(allocation_limit/1024/1024,2) allocation_limit from m_host_resource_utilization;
| ALLOCATION_LIMIT                       |
| -------------------------------------- |
|                                  20480 |

[Former Member]

This message was moderated.

[Former Member]

Hi,

Did u checked the below Thread?

http://www.saphana.com/thread/1335

Regards,

NK

[Former Member]

Hi KC,
Thanks for your link .
The licensed memory ammount is 64G, OS physical memory 20G .The example of my case , I checked all the memory usage, the code and stack , row/column store  table ，the sum total less than the 13G, but cann't set the global_allocation_limit value less than 13G,

I also know hdbindexserver, nameserver will consume memory , but not sure the minimum of allocation memory of HANA  database , on other words ,
what is the minimum of allocation memory of HANA when initial the empty HAVA database.

It semms the minimun memory is 13G of SPS5 and 16G of SPS6 , I think there are lots of memory are pre-allocation, I just want to limit allocation or pre-allocation the total memory of HANA even encounter 'out of memory' errors, Free more memory for other applications.

Thanks

Syni

[former_member193518]

The documentation for rev 70, here http://help.sap.com/hana/SAP_HANA_Administration_Guide_en.pdf

seems to indicate that you should be able to set this to a value as low as 5GB (5 * 1024MB).

[rindia]

Hi Syni Guo,

Whenever you change the configuration files, it will not reflect unless you stop and start the services again in landscape tab or some other place.

Have you done this  before running hdbsql commands?

Also if you give value more than what is available, it will not reflect.

Below is the Example you can find in page 140 of Admin guide:

There is normally no reason to change the value of this variable, unless you purchased a license for less than the total amount of physical memory. In this case, you need to change the global allocation limit to remain in compliance with the license.

A single-host system has 100 GB physical memory. Both the global allocation limit and the individual service allocation limits are 90% (default values).

This means the following:

Collectively, all services of the HANA database can use a maximum of 90 GB.

Individually, each service can use a maximum of 90 GB.

Therefore, if 2 services are running and the current memory pool of service 1 is 50 GB, then the effective allocation limit of service 2 is 40 GB. This is because service 1 is already using 50 GB and together they cannot exceed the global allocation limit of 90 GB.

Regards

Raj

[Former Member]

Hi Kumar Salla,

Thanks for your replay , After change the parameter "global_allocation_limit" value, I didn't re-start the system before running hdbsql commands, the system will auto restart the relevant components.

From page 44 of Admin Guide:

5.1 Changing System Properties

To apply your change, you do not have to restart the system. If necessary, the system automatically restarts the relevant components.

I want to limit allocation or pre-allocation the total memory of HANA , Free more memory for other applications.

Thanks

Syni