On September 2015 VMware released VSAN 6.1. VMware has just announced the newest version of VSAN - 6.2 (I think it will be released in March)! VMware really works hard to improve VSAN...

This version provides some long-awaited features and improvements as follows:

Space efficiency - deduplication (fixed block 4KB) and compression (after deduplication, only block than can be compressed under 2KB). Blocks are deduplicated when de-staging from cache tier to capacity tier as shown on the below figure. This feature is enabled on a cluster level, available for all flash VSAN only and is supported with stretch clusters and ROBO edition - features introduced in VSAN 6.1.

(fixed block 4KB) and compression (after deduplication, only block than can be compressed under 2KB). Blocks are deduplicated when de-staging from cache tier to capacity tier as shown on the below figure. This feature is enabled on a cluster level, available for all flash VSAN only and is supported with stretch clusters and ROBO edition - features introduced in VSAN 6.1. RAID-5 (FTT=1) and RAID-6 (FTT=2) Erasure Coding - saving around 30% space and available only for all flash VSAN.

VSAN Quality of Service (QOC) - per VMDK IOP limits.

Support for pure IPv6.

Software checksum (CRC32 algorithm is used). Two level of scrubbing: component and object levels scrubbings.

Client Cache.

Sparse Swap - an advanced host level option to enable the reclaiming of space dedicated to memory. Useful for VDI.

Enhanced VSAN performance and capacity monitoring.

Enhanced Health service.

Update 15.03.2016: VMware released VSAN 6.2. For more information, please follow the Release Notes.