Saturday, December 14, 2013

ESXi Host reports VMFS heap warnings

  •     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.

  •  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:


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
16 MB
128 MB
80 MB
256 MB

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