VMFS Heap Size error messages
I subscribe to a large number of virtualisation feeds and the primary reason is that I never fail to learn something new every single day.
I came across a blog entry by the excellent Duncan Epping over at Yellow Bricks about VMFS Heap size configuration. I was not previously aware of this setting because we have 3.0.x in our environment and our HP MSA storage only support 3.6Gb fully populated so this scenario would never come up. I will however be keeping this in mind when designing our new ESX 3.5 environment. We seem to be utilising bigger hosts all the time and when you add in a new EMC Clariion CX4, the potential for one host to be accessing more than 4TB of open VMDKs goes up.
was talking to a fellow consultant today. He ran into the following error messages at one of his customer sites:
vmkernel: 8:18:59:58.640 cpu2:1410)WARNING: Heap: 1370: Heap_Align(vmfs3, 4096/4096 bytes, 4 align) failed. caller: 0×8fdbd0
vmkernel: 8:18:59:58.640 cpu2:1410)WARNING: Heap: 1266: Heap vmfs3: Maximum allowed growth (24) too small for size (8192)During the conversation I knew I’d seen this problem before. But the problem that I witnessed was related to a high threshold value in Vizioncore vFoglight. I knew it was possible to change the setting:
- Open vCenter, and click a specific host
- Click on the “Configurations” tab
- Click on Advanced Settings, VMFS3
- Change the value of “VMFS3.MaxHeapSizeMB”
The default value is 16MB, this allows for a maximum of 4TB of open vmdk’s on a single host. The max setting is 128MB which allows for a maximum of 32TB of open vmdk’s on a single host. Keep this in mind when designing your environment.
Keep in mind that this is ESX 3.5 only, you can’t change the heap size in ESX 3.0.x.
