1898317 - How to handle HANA Alert 1: ‘Host physical memory usage’

Symptom

When checking the Alerts tab in HANA Studio and Solution Manager, there is an alert with description "<host name> runs out of physical memory! Installed memory: <memory value>, instance used <memory value>, instance used physical <memory value>”.

Environment

SAP HANA Database

Reproducing the Issue

For HANA Studio, you can find the alert by going to Administration Console -> Alert -> Show: all alert with filter “Installed” (also see attached screenshots).

For Solution Manager, you can find the alert by going to transaction code DBACOCKPIT -> choose HANA system -> expand Current Status -> Alerts (also see attached screenshots).

Cause

Normally there are 2 reasons for this alert:
1. The threshold value of "Check host free physical memory" in "Configure Check Settings" is too low. The default value are Low: 100, Medium: 150, High:200.

2. The other possible reason for this host free memory alert is that an out of memory issue occurs on the HANA system. Either a memory leak, because of old versions do not have the automatic memory release mechanism, or a certain process that is consuming too much memory might lead to an OOM issue.

Resolution

1. The alert triggered due to an improper threshold value setting can be resolved by resetting it to the default or a higher threshold value.

2. The alert triggered due to an OOM issue can be resolved as follows:

• First you need to check the version of HANA DB and upgrade it to the latest version if you are using an old HANA Revision.
• Second, if the alert still occurs, you could try to unload the unused huge tables from the memory, and also, find out, which process (es) is consuming so much memory.
  The huge tables can be found in “System Information” -> “Schema Size (MB) for loaded tables” and “Size of tables on disk”.

• For a more detailed root cause analysis of the memory usage please see the information in the SAP Knowledge Based Article 1840954 - Alerts related to HANA memory consumption. 

3. Restart the HANA database.

Keywords

 threshold; Check host free physical memory; OOM; out of memory; memory utilization; Schema Size (MB) for loaded tables; Size of tables on disk;