Configuring Space Efficiency Technologies in VSAN 6.2

Virtual SAN 6.2 introduces space efficiency features optimized for modern all-flash storage. You can use space efficiency techniques to reduce the amount of space for storing data. Space efficiency features available in VSAN 6.2 are :

  • Deduplication and Compression on a Virtual SAN Cluster.
  • RAID 5 and RAID 6 erasure coding using Failure tolerance method policy attribute on VMs.

In this post, we will be covering the configuration of both the space efficiency features.

Deduplication and Compression

Enabling deduplication and compression can reduce the amount of physical storage consumed by as much as 7x. Environments with highly-redundant data such as full-clone virtual desktops and homogenous server operating systems will naturally benefit the most from deduplication. Deduplication and compression is a single cluster-wide setting that is disabled by default and can be enabled using a simple drop-down menu. This process does not incur virtual machine downtime and can be done online. The compression algorithm is applied after deduplication has occurred just before the data is written to the capacity tier.

When you enable deduplication and compression on a Virtual SAN all-flash cluster, redundant data within each disk group is reduced. Deduplication removes redundant data blocks, whereas compression removes additional redundant data within each data block. You can enable deduplication and compression as a cluster-wide setting, but they are applied on a disk group basis. The amount of storage reduction from deduplication and compression depends on the type of data stored and the number of duplicate blocks.

Deduplication and Compression Design Considerations :

  • Only available on ALL Flash Disk Groups.
  • On-disk format version 3.0 or later is required.
  • Storage-claiming method should be set to manual. Storage-claiming method to automatic after deduplication and compression has been enabled.
  • Capacity overhead for deduplication and compression is approximately five percent of total raw capacity.
  • Using policies with 100 percent proportional capacity reservations can make deduplication and compression less efficient.
  • Virtual SAN can eliminate duplicate data blocks within each disk group, but not across disk groups.

Procedure to configure Deduplication and Compression

Login to vSphere Web Client. Select the Cluster –> Manage –> Settings. Click on Edit to enable Deduplication and Compression.

Screenshot-18Select Enabled from the drop down list.Screenshot-19

Screenshot-20Once Deduplication and Compression is enabled. Virtual SAN performs a rolling reformat of every disk group on every host.
Screenshot-21It will take some time to get the duplication blocks of data removed. You can check the results of deduplication and compression by viewing the Deduplication and Compression Overview in the Virtual SAN Capacity monitor.


Configuring RAID 5 or RAID 6 Erasure Coding

You can use RAID 5 or RAID 6 erasure coding to protect against data loss and increase storage efficiency with same level of data protection as provided in RAID 1, while using less storage capacity.


Below is the Host Requirements Based on Failure Tolerance Method. Due to the host or fault domain requirements of the RAID-5/6 (Erasure Coding) rule, Virtual SAN Stretched Cluster and 2 node configurations are not supported.


In VSAN 6.2, RAID5 and RAID6 technologies, there is no “parity host” and data parity can be on any capacity device.


RAID 5 and RAID 6 Design Consideration

  • On-disk format version 3.0 or later is required to support RAID 5 or RAID 6.
  • RAID 5/6 is not supported on stretched clusters.
  • RAID 5 or RAID 6 erasure coding is available only on all-flash disk groups.
  • Additional space savings by enabling deduplication and compression on the Virtual SAN cluster.

Procedure to configure RAID 5 and RAID 6.

RAID 5 and RAID 6 can be made available using VSAN policy. If FTT = 1 is configured in VSAN Policy, RAID 5  will get configure on the Virtual Machine disk.


Assign the VSAN Policy to the Virtual machine.



If FTT = 2, RAID 6 will be get configured on Virtual Machine disk.



This concludes the configuration of VSAN Storage efficiency techniques in VSAN 6.2. I hope this is informative for you. Thanks for reading !!!. Be social and share it in social media, if you feel worth sharing it.