How To Fix VIRT421 - Memory Ballooned

SAP Error Message - Details

• Message type: E = Error

• Message class: VIRT - Virtualization Monitoring

• Message number: 421

• Message text: Memory Ballooned

What causes this issue?

Amount of memory that is seen by the OS but currently loaned to other
VSs (Ballooned)
.&SYSTEM_RESPONSE&

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message VIRT421 - Memory Ballooned ?

  The SAP error message "VIRT421 Memory Ballooned" typically indicates that the virtual machine (VM) running the SAP system is experiencing memory pressure. This situation arises when the hypervisor (like VMware or another virtualization platform) is reclaiming memory from the VM to allocate it to other VMs that may need it more urgently. This process is known as "memory ballooning."
  Cause:
  
  Memory Overcommitment: The hypervisor has allocated more memory to VMs than is physically available on the host. When the host runs low on memory, it starts reclaiming memory from VMs using ballooning.
  High Memory Usage: The SAP application or other processes running on the VM are consuming a significant amount of memory, leading to pressure on the available resources.
  Insufficient Physical Memory: The physical memory on the host server may be insufficient to support the workloads of all running VMs.
  
  Solution:
  
  Increase Physical Memory: If possible, add more physical RAM to the host server to alleviate memory pressure.
  Adjust VM Memory Allocation: Review and adjust the memory allocation for the VMs. Ensure that the memory assigned to each VM is appropriate for its workload.
  Optimize SAP Configuration: Review the SAP system configuration to optimize memory usage. This may include tuning parameters related to buffer sizes, work processes, and other memory-intensive settings.
  Monitor Memory Usage: Use monitoring tools to keep an eye on memory usage patterns. This can help identify which processes or applications are consuming excessive memory.
  Disable Ballooning: If ballooning is causing significant performance issues and you have sufficient resources, consider disabling memory ballooning for the VM. However, this should be done with caution, as it may lead to other VMs being starved of memory.
  Use Resource Pools: If using a hypervisor that supports resource pools, consider creating resource pools to manage memory allocation more effectively among VMs.
  
  Related Information:
  
  VMware Tools: Ensure that VMware Tools (or equivalent for other hypervisors) are installed and up to date, as they help manage memory and other resources effectively.
  SAP Notes: Check SAP Notes for any specific recommendations or patches related to memory management and performance tuning for your version of SAP.
  Performance Monitoring: Utilize SAP's performance monitoring tools (like ST03N, ST06) to analyze memory usage and identify bottlenecks.
  
  By addressing the underlying causes of memory ballooning and optimizing resource allocation, you can mitigate the impact of the VIRT421 error and improve the performance of your SAP system.