ESXi Host reports VMFS heap warnings

Setup
  •     VMware vCenter 5.1
  •     ESXi 5.1 GA build (799733)

Purpose of Heap Size
The main consumer of VMFS heap are the pointer blocks which are used to address file blocks in very large files/VMDKs on a VMFS filesystem. Therefore, the larger your VMDKs, the more VMFS heap you can consume. This is more true on VMFS-5, where double-indirect pointers exist to allow the unified 1MB file block size back a 2TB VMDK.
Discoveries
  •  Having issues with VM which has 1.5 TB vmdk due to Heap Size. VMkernal logs displays following

cpu6:5423797)WARNING: Heap: 2638: Heap vmfs3 already at its maximum size. Cannot expand.
2013-08-23T01:44:24.308Z cpu6:5423797)WARNING: Heap: 3019: Heap_Align(vmfs3, 2099216/2099216 bytes, 8 align) failed.  caller:
0x418007a172c4 
Resolution/WorkAround
As per this build we have have maximum of 256 MB heap value where 80MB is the default value.
We followed given article to increase the heap size
ESXi Version
Default
Maximum
3.5/4.X
16 MB
128 MB
5.X
80 MB
256 MB

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