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An ESX host reports vmfs heap warnings when hosting virtual machines that collectively use 4TB of virtual disk storage
Symptoms
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ESX host has more that 4 terabytes (TB) of virtual disks (.vmdk files) open.
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Warnings similar to the following are found in /var/log/vmkernel or the /var/log/messages log:
vmkernel: 8:18:59:58.640 cpu2:1410)WARNING: Heap: 1370: Heap_Align(vmfs3, 4096/4096 bytes, 4 align) failed. caller: 0x8fdbd0
vmkernel: 8:18:59:58.640 cpu2:1410)WARNING: Heap: 1266: Heap vmfs3: Maximum allowed growth (24) too small for size (8192)
Purpose
Resolution
The default heap size in ESX 3.5/4.0 for VMFS-3 is set to 16MB. This allows for a maximum of 4TB of open virtual disk capacity on a single ESX host. The default heap size has been increased in ESX 4.1 to 80M, which allows for 20TB of open virtual disk capacity on a single ESX host.
To adjust the value:
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Log in to vCenter Server or the ESX host using VMware Infrastructure (VI) Client. If connecting to vCenter Server, select the ESX host from the inventory.
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Click the Configuration tab.
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Click Advanced Settings.
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Select VMFS3.
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Update the field in VMFS3.MaxHeapSizeMB.
Note: The maximum heap size is 128MB. This allows a maximum of 32TB of open storage. - Reboot the ESX host for the changes to take affect.
Additional Information
- This article does not apply to ESXi 5.x, if you are using VMFS-3 on the ESXi 5.x host.
- However this issue can occur on ESXi 5.0 if you are using a VMFS5 datastore which has been converted from VMFS3.
- In ESX 3.0, the VMFS3.MaxHeapSizeMB value cannot be modified.
- In ESX 4.1, by default, the VMFS3.MaxHeapSizeMB option is set to 80MB. This value can be modifed and set to a value between the range of 16MB to 128MB. A higher value increases the threshold at which these warnings are reported.
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