This is the fourth major release of VSAN functionality. VMware is definitely taking this product seriously and trying to evolve VSAN to a true enterprise-grade SDS stack.
If you are a customer that has an extensive investment in the VMware eco-system from a people, process and technology perspective, then VSAN could be a good choice if you are dipping your toes into the HCI space for a small part of your infrastructure. Use-cases such as Management, DMZ, PCI, Dev/Test and EUC Clusters are a great fit, in my opinion. If you are selecting an enterprise-wide solution for mission/business critical applications, then a more mature SDS vendor would be worth considering to minimise risk.
Here is the list of current weaknesses I have found during testing and conversations with my industry peers:
- Quality of vSphere 6.0 releases is inconsistent and buggy, this obviously directly impacts the introduction of new VSAN functionality. Customers will need to mitigate this risk through extensive testing before releasing vSphere patches and functionality to Production infrastructure.
- VMware GSS support for VSAN is lacking.
- If a flash drive fails, the entire disk group fails.
- Adding more flash requires additional disk groups on hosts (hybrid only).
- If a disk reaches 50ms of latency it will be removed from the disk group. If a flash drive reaches 50ms of latency, the whole disk group is removed. UPDATE: Changes made in 6.2 to correct this.
- Lack of VCAI support for VSAN.
- VSAN Caching software is licenced from IBM.
- 70/30 R/W ratio of VSAN Cache cannot be changed (hybrid only).
VSAN 6.2 in a nutshell (more detail below):
- Deduplication and Compression for All-Flash only
- Erasure Coding (equivalent RAID-5 for FTT1, RAID-6 for FTT2) for All-Flash only
- Software Checksum for Data Integrity
- Support for IPv6-only mode
- SAP Core Ready
- Enhanced Horizon integration
- Oracle RAC supported
- vSphere Web Client with new Health Service (Performance and Capacity Monitoring)
- Health Check plugin no longer required, VSAN Observer no longer required
- Client Cache (boost random read performance) and Sparse Swap (reclaim storage)
- Firmware updates for controllers via Health UI for Hybrid configurations
- Improved vROps integration