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Datastore / Virtual Machine Storage Capacity Counters

Performance counters are modeled using the PerfCounterInfo data object type. Each instance of a PerfCounterInfo data object contains metadata about a specific metric available from the system. The disk group of counters support metrics for I/O (input/output) performance (such as latency and read- and write-speeds), and utilization metrics for storage as a finite resource. This page includes documentation for storage-utilization counters only. See the Disk I/O Counters page for information about disk I/O counters.

A datastore is a logical construct, conceptually similar to a “volume.” A datastore provides an abstraction of the underlying LUNs (logical unit numbers), which provide the actual physical storage. The storage-utilization counters measure various aspects of datastore space.

Some key points about storage utilization:

  • A datastore can comprise numerous virtual machines.
  • A virtual machine comprises numerous files, including swapfiles, virtual disk files, snapshot files, configuration files, log files.
  • A virtual machine can span more than one datastore.
  • “Aggregate” refers to “datastore or virtual machine as a whole.”

The instance property of the metric ID identifies the device associated with a metric returned from the system. Conversely, device information can be set in the instance property, in the PerfQuerySpec’s optional metricId and passed to a PerformanceManager query operation to return storage utilization information for specific virtual machines or filetypes. The descriptions below include this information.

These counters are available from vCenter Server only (not directly from ESX).

Values are populated every 30 minutes.

Counter StatsType Unit Level RollupType Label
capacity absolutekiloBytes1latestStorage Capacity
Configured size of the datastore. Available from a datastore entity only.
provisioned absolutekiloBytes1latestStorage Space Potentially Used
Amount of storage set-aside for use by a datastore or virtual machine. Files on the datastore and the virtual machine can expand to this size, but not beyond it. Available from datastore and virtual machine target entities.

Datastore:
  • To obtain aggregated space set-aside for use for the entire target datastore, set the instance property of the metric ID to an empty string (" ").
  • To obtain aggregated space provisioned for a specific virtual machine on the target datastore, set the instance property to the virtual machine identifier.
Virtual machine:
  • To obtain aggregate space provisioned for the target virtual machine, set the instance property of the metric ID to an empty string (" ").
unshared absolutekiloBytes1latestStorage Space Not Shared
Amount of space associated exclusively with a virtual machine. Available from datastore and virtual machine target entities.
  • Datastore: Values are an aggregate of unshared space on a datastore, per virtual machine. Instance property of the PerfMetricId is set to the identifier of the virtual machine.
  • Virtual machine: Values are an aggregate of all unshared space for the virtual machine across all datastores. The instance property of the metric ID is “Unset.” (Set instance to empty string (" ") to obtain aggregate unshared space for the virtual machine across all datastores.)
used absolutekiloBytes1latestStorage Space Actually Used
Amount of space actually used by the virtual machine or the datastore. May be less than the amount provisioned at any given time, depending on whether the virtual machine is powered-off, whether snapshots have been created or not, and other such factors. Available from datastore and virtual machine target entities.
Datastore:
  • To obtain aggregated space used by the datastore, set the instance property of the metric ID to an empty string (" ").
  • To obtain aggregated space used by a specific virtual machine on the target datastore, set the instance property to the virtual machine identifier.
  • To obtain aggregated space used by all files of a specific type on the datastore, set the instance property to a valid filetype, specifically:
    • DISKFILE, which comprises the base disk of a virtual machine's disk and delta disks
    • DELTAFILE, which comprises virtual machine Snapshot overhead files
    • SWAPFILE, for virtual machine swap files
    • OTHERFILE, for all other virtual machine files
Virtual machine:
  • To obtain aggregated datastore space used by the target virtual machine, set the instance property of the metric ID to an empty string (" ").
  • To obtain aggregated space used by the virtual machine for files of a specific type, set instance property of the metric ID to a valid filetype:
    • DISKFILE, which comprises the base disk of a virtual machine's disk and delta disks
    • DELTAFILE, which comprises virtual machine Snapshot overhead files
    • SWAPFILE, for virtual machine swap files
    • OTHERFILE, for all other virtual machine files

 

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