Enable vSphere Storage I/O Control Datastores

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A few words about Storage I/O Control on datastores

vSphere Storage I/O Control allows cluster-wide storage I/O prioritization, which allows better workload consolidation and helps reduce extra costs associated with over provisioning. When you enable Storage I/O Control on a datastore, ESXi begins to monitor the device latency that hosts observe when communicating with that datastore.

When device latency exceeds a threshold, the datastore is considered to be congested and each virtual machine that accesses that datastore is allocated I/O resources in proportion to their shares. You set shares per virtual machine. You can adjust the number for each based on need.

How to enable? Go to datastore, right click Configuring Storage I/O Control as image below.

And here you have 3 options:

  1. Enable Storage I/O Control + Statistic collection
  2. Disable Storage I/O Control ,  enable just statistic collection
  3. Disable both.

In 2 words, why this is needed?

When you enable Storage I/O Control on a datastore, ESXi host starts to monitor the device latency that hosts observe when communicating with that datastore. When device latency exceeds a threshold, the datastore is considered to be congested and each VM that accesses that datastore is allocated I/O resources in proportion to their shares.

Storage I/O Control operates as a “datastore-wide disk scheduler.” Once Storage I/O Control has been enabled for a specific datastore, it will monitor that datastore, summing up the disk shares for each of the VMDK files on it. Storage I/O Control will then calculate the I/O slot entitlement per ESXi host based on the percentage of shares virtual machines running on that host have relative to the total shares for all hosts accessing that datastore.

More informaton read here > https://kb.vmware.com/s/article/1020651

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