Heaping Heaps! – ESX Heap Size

Mr. Epping over at Yellow-Bricks posted this on VMFS3 Heap Size. I’m reposting here for future reference.

I 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 Veeam vFoglight. I knew it was possible to change the setting:

   1. Open vCenter, and click a specific host
   2. Click on the “Configurations” tab
   3. Click on VMFS3
   4. 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 on ESX 3.0.x