You can use advanced VMFS parameters to configure pointer block cache.

As the size of virtual machine files on VMFS datastores increases, the number of pointer blocks used by those files also increases. Pointer blocks are used to address file blocks in large virtual machine files and virtual disks on a VMFS datastore.

You can configure the minimum and maximum sizes of the pointer block cache on each ESXi host. When the size of the pointer block cache approaches the configured maximum size, an eviction mechanism removes some pointer block entries from the cache to allow for new pointer blocks to be read in.

Base the maximum size of the pointer block cache on the working size of all open virtual disk files that reside on VMFS datastores. All VMFS datastores on the host use a single pointer block cache.

The minimum value is based on the minimum guaranteed memory that the system can allocate to the cache. 1TB of open file space requires approximately 4MB of memory.

Use the following parameters to configure the minimum and maximum values for pointer block cache.

Table 1. Advanced Parameters to Regulate Pointer Block Cache

Parameter

Values

Description

VMFS3.MaxAddressableSpaceTB

Default value is 32 (in TB).

Maximum size of all open files that VMFS cache will support before eviction starts.

VMFS3.MinAddressableSpaceTB

Default value is 10 (in TB).

Minimum size of all open files that VMFS cache guarantees to support.

For information about how to configure these advanced parameters, see Set Advanced Host Attributes in the vSphere Web Client.