KBI 311754 New Feature: Enhanced Datastore Volume Rule Monitors Provisioned Space vs Storage Capacity


Argent Advanced Technology 5.1A-1904-C or above


Friday, 17 May 2019


Datastore Volume Rule in Argent for VMware has been enhanced to monitor provisioned space

It can monitor following:

  • Provisioned Space in MB or GB
  • Delta value of Provisioned Space since last check
  • Provisioned to Total Space Difference in MB or GB
  • Provisioned Space over Datastore Capacity in percentage

Provisioned space is the storage space allocated to VMs

When Thin Provisioning is used, the storage space is not immediately allocated

Instead, allocation is done in on-demand manner

As a result, the total of provisioned space could be more than storage capacity

This condition is called Over Provisioning

However, as long as free space is still available, VM’s would be running just fine

Nevertheless, Datastore must be monitored closely in case that Datastore runs out of storage space

By checking the free space, which is also available in Datastore Volume Rule, Argent for VMware can capture the condition that VM’s will soon be crashing

The new feature is even more proactive

By checking the severity of Over Provisioning, Argent for VMware can identify the potential ill-configured system way before VM crashing starts to happen

The new feature is implemented in Argent Advanced Technology 5.1A-1904-C

Technical Background

Provisioned Space = Used Space + Uncommitted Space

Used Space = Datastore Capacity – Free Space

Provisioned to Total Space Difference = Provisioned Space – Datastore Capacity

Provisioned Space over Datastore Capacity (%) = Provisioned Space * 100 / Datastore Capacity

VM using Thin Provision usually has Provisioned Space bigger than actually Used Space

When VM needs more space, system will use free space to allocate more space as long as the total is under Provisioned Space

As a result, Provisioned Space grows while Free Space is reduced

It is a misunderstanding that adding up Provisioned Space and Free Space to compare with Datastore Capacity

If Provisioned Space is lower than Capacity, it is totally safe

If Provisioned Space is a bit over Capacity, it fine as long as Free Space is available

If Provisioned Space is way over Capacity, even Free Space is available, at least it is NOT a good configuration, and VM crashing is very likely to happen


Upgrade to Argent Advanced Technology 5.1A-1904-C or above