NSX Manager constantly displays Memory Utilization at almost 100%
Article ID: 321088
Updated On:
Products
VMware NSX Networking
Issue/Introduction
This article provides information why the NSX Manager displays memory utilization.
Symptoms:
Symptoms:
- NSX Manager displays Memory Utilization at almost 100% constantly
- NSX Manager through the vSphere Web Client displays high Used memory and low Free memory available
- Reboot of NSX Manager drop the memory utilization to significantly lower than 100%. However over time, the utilization value climbs back up to 100% and the display remains at that level
- There are no OutOfMemoryErrors in the NSX Manager logs
- There is no impact observed
Environment
VMware NSX for vSphere 6.2.x
Cause
The NSX Manager is based on Linux where when memory is available on a system, it is used for buffers (file system metadata) and cache (pages with actual contents of files or block devices).
This allows the operating system to run optimally because by making disk information available in RAM, it reduces the requirement for disk I/O.
When systems has been running for a while, it is normal that the reported free memory of the kernel is a small value.
Even though free memory is reported as low, the buffer and cache memory is still available to the application processes that run on the NSX manager.
If buffer or cache memory is required by application processes, it is then freed up on demand. The Free memory reported by the system is therefore not the actual RAM that is available to the core processes running on the NSX Manager.
This allows the operating system to run optimally because by making disk information available in RAM, it reduces the requirement for disk I/O.
When systems has been running for a while, it is normal that the reported free memory of the kernel is a small value.
Even though free memory is reported as low, the buffer and cache memory is still available to the application processes that run on the NSX manager.
If buffer or cache memory is required by application processes, it is then freed up on demand. The Free memory reported by the system is therefore not the actual RAM that is available to the core processes running on the NSX Manager.
Resolution
Additional Information
In order to confirm memory utilization, run the show system memory command on the NSX Manager Command Line Interface (CLI).
For example:
show system memory
MemTotal: 16410596 kB
MemFree: 175836 kB
MemAvailable: 6869908 kB
Buffers: 854528 kB
Cached: 5570524 kB
SwapCached: 2976 kB
Active: 12250008 kB
Inactive: 3524936 kB
Active(anon): 8395104 kB
Inactive(anon): 996396 kB
Active(file): 3854904 kB
Inactive(file): 2528540 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 4202492 kB
SwapFree: 4136392 kB
Dirty: 88 kB
Writeback: 0 kB
AnonPages: 9348896 kB
Mapped: 88808 kB
Shmem: 41608 kB
Slab: 404288 kB
SReclaimable: 371336 kB
Free memory = MemFree + Buffers + SReclaimable + Part of Cached (Cached -Shmem)
Used memory = Part of Cached (shmem) + SUnreclaim + SwapCached + Page Tables + Apps
Used memory = MemTotal - (MemFree + Buffers + SRelaimable + Cached -Shmem)
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