last updated: 2025-08-29
Why was this blog post created?
Countless times we are faced with the fact that the cause of a system performance problem is nothing more than an insufficient amount of “working memory”.
Fact: SAP HANA needs memory. In case the available “working memory” is insufficient the system won’t work properly. General performance issue occurs.
Rule of thumb: the recommendation from SAP is the “tables data” should not use more than 50 % of the available memory.
One stop shop about SAP HANA memory: Collected information about memory in context of SAP HANA
How to check/detect if SAP HANA is having a memory issue?
1. SAP GUI – Transaction Code – DBACOCKPIT (Load History) – some further examples can be found here
In the case of a healthy system, a system in a calm state (e.g. out of working hours or without load) shows a constant used memory value (max. 50% of the available memory). In this case “used memory” = “tables data”. When system used actively next to the “tables data” we see “working memory” also. In this case “used memory” = “tables data” + “working memory”. The “working memory” increase and decrease during the system usage. We can check the memory usage easily with “Load History” option, e.g. Last 7 Days or with Custom Selections, so we can have a high level overview about the memory usage in general.
There is no room for “working memory” because “tables data” use the majority of the available memory all the time.
2. 3284834 – SQL Statement Collection: “HANA_Configuration_Minichecks” report for SAP HANA
The most general report will contain further information about the issue. Number of low memory unloads (short-term) = 226380 and Memory reclaim activity (s / day) = 26154. These are outrageously high numbers.
|M0430|Number of low memory unloads (short-term) | |226380 |0 |X| 2127458|
|M0435|Number of shrink unloads (short-term) | |0 |<= 1000 | | 2127458|
|M0437|Size of unloaded columns (% / day, long-term) | |29.24 |<= 3.00 |X| 2127458|
|M0438|Memory reclaim activity (s / day) | |26154 |<= 1200 |X| 1999997|
|M0439|Memory reclaim maximum duration (s) | |57 |<= 60 | | 1999997|
|M0440|Topology shared memory utilization (%) | |1 |<= 70 | | 1977101|
|M0445|Number of OOM events (short-term) | |5 |<= 3 |X| 1999997|
|M0446|Number of OOM events per day (mid-term) | |6.71 |<= 3.00 |X| 1999997|
|M0447|Number of alloc. limit OOM events (long-term) | |47 |0 |X| 1999997|
3. 3330262 – SQL Statement Collection: “HANA_Memory_Overview” report for SAP HANA
The report makes it easy to identify database tables that are using the majority of memory.
What are the consequences?
When the database does not have enough memory to operate, it tries to resolve the situation, it performs “unloads” and “reclaim” activities. These operations are inherent to the functionality of a healthy system, but in the case of a system constantly struggling with memory problems, they result in a constant and never-ending loop. Continuous reclaim and unload activity results in continuous resource (e.g. CPU) usage. The unloading also could affect a database table(s) that should not be removed from memory because it is in general use, meaning it will be reloaded soon again.
What is the conclusion?
There is no miracle or magic. To handle the high memory footprint you have the following options:
1. Data Management of general tables and technical tables. Reference: 3348393 – Overview of the data management process in the context of SAP HANA
2. Increase the available memory in the system.
Other article
✍️ Where can I find knowledge and information belongs to SAP HANA?
Useful bookmark
🔖 2872774 – Bookmark of Frequently Asked Questions for SAP HANA
🔖 3311408 – Bookmark of SQL Statement Collection reports for SAP HANA
🔖 2658020 – List of SAP HANA SQL Error Codes
Do you have further questions?
Please do not hesitate to contact me if you have question or observation regarding the article.
Q&A link for SAP HANA: https://answers.sap.com/tags/73554900100700000996
Contribution
If you find any missing information belongs to the topic, please let me know. I am happy to add the new content. My intention is to maintain the content continuously to keep the info up-to-date.
Release Information
Release DateDescription2025.08.29First/initial Release of the SAP Blog Post documentation (Technical Article).
last updated: 2025-08-29Why was this blog post created?Countless times we are faced with the fact that the cause of a system performance problem is nothing more than an insufficient amount of “working memory”.Fact: SAP HANA needs memory. In case the available “working memory” is insufficient the system won’t work properly. General performance issue occurs.Rule of thumb: the recommendation from SAP is the “tables data” should not use more than 50 % of the available memory.One stop shop about SAP HANA memory: Collected information about memory in context of SAP HANAHow to check/detect if SAP HANA is having a memory issue?1. SAP GUI – Transaction Code – DBACOCKPIT (Load History) – some further examples can be found hereIn the case of a healthy system, a system in a calm state (e.g. out of working hours or without load) shows a constant used memory value (max. 50% of the available memory). In this case “used memory” = “tables data”. When system used actively next to the “tables data” we see “working memory” also. In this case “used memory” = “tables data” + “working memory”. The “working memory” increase and decrease during the system usage. We can check the memory usage easily with “Load History” option, e.g. Last 7 Days or with Custom Selections, so we can have a high level overview about the memory usage in general.There is no room for “working memory” because “tables data” use the majority of the available memory all the time.2. 3284834 – SQL Statement Collection: “HANA_Configuration_Minichecks” report for SAP HANAThe most general report will contain further information about the issue. Number of low memory unloads (short-term) = 226380 and Memory reclaim activity (s / day) = 26154. These are outrageously high numbers.|M0430|Number of low memory unloads (short-term) | |226380 |0 |X| 2127458|
|M0435|Number of shrink unloads (short-term) | |0 |<= 1000 | | 2127458|
|M0437|Size of unloaded columns (% / day, long-term) | |29.24 |<= 3.00 |X| 2127458|
|M0438|Memory reclaim activity (s / day) | |26154 |<= 1200 |X| 1999997|
|M0439|Memory reclaim maximum duration (s) | |57 |<= 60 | | 1999997|
|M0440|Topology shared memory utilization (%) | |1 |<= 70 | | 1977101|
|M0445|Number of OOM events (short-term) | |5 |<= 3 |X| 1999997|
|M0446|Number of OOM events per day (mid-term) | |6.71 |<= 3.00 |X| 1999997|
|M0447|Number of alloc. limit OOM events (long-term) | |47 |0 |X| 1999997|3. 3330262 – SQL Statement Collection: “HANA_Memory_Overview” report for SAP HANAThe report makes it easy to identify database tables that are using the majority of memory.What are the consequences?When the database does not have enough memory to operate, it tries to resolve the situation, it performs “unloads” and “reclaim” activities. These operations are inherent to the functionality of a healthy system, but in the case of a system constantly struggling with memory problems, they result in a constant and never-ending loop. Continuous reclaim and unload activity results in continuous resource (e.g. CPU) usage. The unloading also could affect a database table(s) that should not be removed from memory because it is in general use, meaning it will be reloaded soon again.What is the conclusion?There is no miracle or magic. To handle the high memory footprint you have the following options:1. Data Management of general tables and technical tables. Reference: 3348393 – Overview of the data management process in the context of SAP HANA2. Increase the available memory in the system.Other article✍️ Where can I find knowledge and information belongs to SAP HANA?Useful bookmark🔖 2872774 – Bookmark of Frequently Asked Questions for SAP HANA🔖 3311408 – Bookmark of SQL Statement Collection reports for SAP HANA🔖 2658020 – List of SAP HANA SQL Error CodesDo you have further questions?Please do not hesitate to contact me if you have question or observation regarding the article.Q&A link for SAP HANA: https://answers.sap.com/tags/73554900100700000996ContributionIf you find any missing information belongs to the topic, please let me know. I am happy to add the new content. My intention is to maintain the content continuously to keep the info up-to-date.Release InformationRelease DateDescription2025.08.29First/initial Release of the SAP Blog Post documentation (Technical Article). Read More Technology Blog Posts by SAP articles
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