Because SAP High Performance Analytic Appliance is an in-memory database, understanding how its memory limits work is critical if you want to use it successfully. Our overview here will explain what the SAP HANA memory limit is, the terms that you can associate with memory, and how the system uses the memory to store data or finish tasks.
Memory is a finite resource within any SAP HANA system, so it is important for you to know how much of it is available to you. The database’s core strength is how it stores data within the RAM and retrieves it in real-time. Therefore, the SAP HANA memory limit is a critical aspect that has a big impact on the overall effectiveness of the system.
SAP HANA Memory Usage
SAP HANA is an umbrella program that runs several processes in SUSE Linux. One of the primary functions of any operating system is to allocate memory to each process as necessary. When you boot up SAP HANA, the OS will reserve space for the program code or stack. The system keeps this memory in reserve but can redirect additional memory to SAP HANA’s memory manager upon request. In many cases, SAP will request additional memory from the OS before it needs to use that memory for any processes. It does this because keeping track of how much memory it consumes is vital for it to function properly.
SAP HANA Used Memory
You can find the amount of memory SAP HANA requests in a shared pool that defines the upper SAP HANA memory limit. This pool includes various tables, thread stacks, and computations that the system might need. SAP HANA only uses certain parts of this pool at any given point in its operations. We refer to whatever memory SAP uses as used memory. Keep in mind that you can partition large tables or data sets or spread them across multiple systems if you need to keep the memory usage in check.
More Resources for SAP HANA Enthusiasts:
SAP HANA Memory Limits
The SAP HANA memory limit can range from 256 gigabytes to two terabytes in size. Keep in mind that this total memory amount is what you’ll use to run Linux, SAP HANA itself, and any processes that SAP uses. In addition to this general memory partition, each process typically has a set amount of memory it can use to run. Therefore, the more processes you think you’ll need to run, the more memory you should allocate to the program. There are a few terms you should know if you want to fully understand these limits.
This is the total amount of memory available on the machine. This number changes when you divide the memory into various partitions.
Memory Allocation Pool
This is the amount of memory that the OS (Linux) allocates to the SAP HANA architecture. Here, you’ll find the total amount of memory available in SAP. The Physical Memory category displays the total amount of memory for the entire system.
This number represents the maximum amount of memory that Linux can give to SAP HANA. It is usually part of SAP’s best practices to set this amount to the maximum allowable limit based on the license you use.
Exceeding the SAP HANA Memory Limit
Because memory is a finite resource, it is important that you respect how much of it is available. Indeed, SAP can continue to function if you exceed the memory limit. However, it cannot function at the same level if it is working on reduced memory parameters.
Like any machine, the SAP HANA database has requirements it must meet in order to function. Memory is one of the basic things SAP needs. If it runs out of available memory, it will try to find ways to recycle it. The system will drop caches of information or tables that might be critical to your work in an effort to find the memory it needs to continue computing. In short, if you do not respect the limits of the memory allocated to SAP, you could lose critical data and hours of hard work.
The problem may multiply as the system continues unloading data. SAP will release caches starting with the ones you have not used recently. This will free up more memory but lead to a dip in performance later. The negative effects here will become more noticeable to you as you continue to use the database. SAP’s core advantage consists in how it can access data based on your queries. You will have to reload the data sets that the system released earlier. This reloading will make the data retrieval process much slower overall.
Setting Limits for SQL Statements
If you don’t want to run the risk of going over the memory limit within SAP, you can set a limit that prevents any single statement from going over its allocated memory parameters. Please note that you will need the INIFILE ADMIN system privilege to be able to tweak these limits.
Enable Statement Tracking
Go to the “global.ini” file and expand its “resource_tracking” section. Turn both “enable_tracking” and “memory_tracking” to the ‘On’ position. You will see here that the default value is zero. This means you haven’t set any limits.
Set a Value
Choose a value within the memory manager between one gigabyte and the allocation limit. If the value you choose is smaller than that, it could interfere with critical tasks. Please note that once you set this parameter, the system will cease any statements that exceed it.
Determine the Threshold
You can set the threshold at a percentage of the total memory allocated to the system. This will show you if a single statement is consuming far more memory than the rest of the system. If the system says it is, it will drop it in order to preserve memory for other statements.
Being able to store and retrieve data quickly is one of the core strengths of the SAP database. The SAP HANA memory limit helps to define the top capabilities of the in-memory system. Plus, it prevents any processes from taking too many resources. What do you think about these limits? Let us know in the comments section below!
Check Out More Articles: