6.7

Table 17‑7. VOMA Command Options (Continued)
Command Option Description
-v | --version
Display the version of VOMA.
-h | --help
Display the help message for the VOMA command.
For more details, see the VMware Knowledge Base article 2036767.
Configuring VMFS Pointer Block Cache
Pointer blocks, also called indirection blocks, are file system resources that contain addresses to VMFS
file blocks. When you open a vmdk file on an ESXi host, pointer blocks related to that file are stored in the
pointer block cache. The size of the pointer block cache is a configurable parameter.
The pointer block cache is a host-wide cache that is independent from VMFS. The cache is shared
across all datastores that are accessed from the same ESXi host.
The size of the pointer block cache is controlled by /VMFS3/MinAddressableSpaceTB
and /VMFS3/MaxAddressableSpaceTB. You can configure the minimum and maximum sizes on each
ESXi host.
/VMFS3/MinAddressabl
eSpaceTB
The minimum value is minimum amount of memory that the system
guarantees to the pointer block cache. For example, 1 TB of open file
space requires approximately 4 MB of memory. Default value is 10 TB.
/VMFS3/MaxAddressabl
eSpaceTB
The parameter defines the maximum limit of pointer blocks that can be
cached in memory. Default value is 32 TB. Maximum value is 128 TB.
Typically, the default value of the /VMFS3/MaxAddressableSpaceTB
parameter is adequate.
However, as the size of the open vmdk files increases, the number of
pointer blocks related to those files also increases. If the increase causes
any performance degradation, you can adjust the parameter to its
maximum value to provide more space for the pointer block cache. Base
the maximum size of the pointer block cache on the working set, or the
active pointer blocks required.
Pointer Block Eviction The /VMFS3/MaxAddressableSpaceTB parameter also controls the growth
of the pointer block cache. When the size of the pointer block cache
approaches the configured maximum size, a pointer block eviction process
starts. The mechanism leaves active pointer blocks, but removes non-
active or less active blocks from the cache, so that space can be reused.
To change the values for the pointer block cache, use the Advanced System Settings dialog box of the
vSphere Client or the esxcli system settings advanced set -o command.
You can use the esxcli storage vmfs pbcache command to obtain information about the size of the
pointer block cache and other statistics. This information assists you in adjusting minimum and maximum
sizes of the pointer block cache, so that you can get maximum performance.
vSphere Storage
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