VMware vSAN 6.7

By | April 28, 2018

Just one year ago, VMware has announced vSAN 6.6… now it’s the turn of  vSAN 6.7, contextually of the release of vSphere 6.7 GA.

VMware vSAN is the VMware’s Software Defined Storage (SDS) solution that also fits in the hyper(visor)-converged model to build a simple (to be managed) and scalable HCI solution. Although is a separate product, the core functions to implement it are already present in the vSphere versions making really easy to deploy and enable it.

VMware vSAN 6.7 What’s New?

Adaptive Resync – dynamic management of resynchronization and VM traffic. While the previous release of VMware vSAN allowed putting a manual threshold on the resync operations and also to split large components during redistribution, the vSAN 6.7 goes much further and allows adaptive resync.

Adaptive resync will ensure that a fair allocation of resync resources are available for VM IO (IOPS consumed by VMs) and resync IO (IOPS consumed by the backend storage tasks). It all will happens during dynamic changes and load on the system. The adaptive resync will guarantee the level of bandwidth to ensure that specific traffic type will not starve from resources.

VMware vSAN 6.7 adaptive resync

Faster Destaging – VMware has improved the in-memory handling of I/O during destaging. In fact, during the destage process from the write buffer to the capacity tier. So the buffer is available for new IOs much quicker.

This optimization provides better performance not only for VM I/O but also for the resynchronization I/O.

VMware vSAN 6.7 faster destaging

vSAN Replica Consolidation – It consolidates replicas which are stored across multiple fault domains (hosts) while maintaining FTT compliance. Before you shut down, you need to put host to a maintenance mode. You also need to select an evacuation method (Ensure data accessibility from other hosts, Evacuate All data to other hosts, or No data evacuation)…

The new improvement:

  • Opens up fault domain as a target for other objects during decommissioning.
  • It also looks for the smallest component to move.
  • As a result, there is fewer data rebuilt and less temporary space usage.

Space efficiency improved via New Object Provisioning – It brings new behaviors with swap file objects for space efficiency. The new swap objects are thin provisioned.

  • VM swap now Thin provisioned (previously an advanced parameter had to be set on a per-host basis).
  • A policy will be inherited from VM instead of the Default vSAN storage policy
  • FTT on swap object consistent with applied object policy

Fast Failovers when using Redundant vSAN networks – An Improved resilience of redundant vSAN networks.

New logic has been introduced.

  • Each vmknic is on a different subnet
  • no connectivity between switches
  • There is an immediate failover to other fabric when there is a failure of vmknic in one fabric

Optimized Witness Traffic separation for stretched clusters – if you’re running an architecture with a stretched cluster environment, you’ll have a possibility now to benefit from the improved separation of witness traffic from vSAN data traffic. The new improvements will prevent data traffic from being routed via vmknic for witness host traffic when there is a link failure.

It’s configured by specifying an alternate vmknic (by ESXCLI command only in this release). This was previously supported already for 2-Node configurations.

Failure handling improved in case of stretched cluster architecture – you’re in a situation of a site isolation.  The inter site link is down (ISL) but also the link to the third site where the witness is located, is down as well.

In order to track the component health properly, in a situation when the connectivity to the Witness site is back again, vSAN will track the fitness of each site after full partition event of the Preferred site. The secondary site is maintained as an Active site until ISL connectivity is restored.

It prevents false positives when the ISL is not “up”.

Host Affinity for Next-Gen Applications – you can now “pin” a VM to a certain node.

The system makes sure that data stays on the same host that VM runs.

VMware vSAN 6.7 Host Affinity for Next-Gen Applications

Stretched Cluster Efficient Resync with Proxy Owner – this feature’s goal is to reduce inter-site traffic. It minimizes the data which travels across WAN link.

It designs a proxy owner on the target site (Site B in our example) which takes advantage of local resync.

  • The partial resync will sync active replica across ISL.
  • It will establish proxy owner to manage local resync.
  • Resync of the replica on site B will occur from a local copy.

Support for Windows Server Failover Clusters (WSFC) – now it supports the legacy storage architectures. iSCSI service which can be activated on the VMware vSAN cluster can present shared storage to those WSFC servers and the solution is fully supported. It supports either:

  • Physical – Using guest iSCSI initiator
  • Virtual – Using guest iSCSI initiator

VMware vSAN iSCSI and failover cluster support

vSAN Support Insight – when enabled, the data are anonymized and then uploaded to VMware. And it is VMware which is able to help when you’re experiencing problem or performance struggle. The pieces of information (such as names of hosts, or VMs) are changed before that information is uploaded to VMare.

Health Checks Additions and Improvements – there are some improvements on the health checks for vSAN 6.7 as well. Those health checks are very useful to troubleshoot or avoid problems.

  • New host maintenance mode verification ensures proper decommission state
  • New host consistency settings verification for advanced settings
  • Improved vSAN and vMotion Network connectivity checks
  • Improved vSAN health Service Installation check
  • Improved physical disk health check combines multiple checks (software, physical, metadata) into one check
  • Improved HCL check; firmware check now independent from driver check

Enhanced Diagnostic Partition (coredump) Support – for diagnosing issues properly, there is a coredump partition. It is a special partition for diagnostic purposes. VMware vSAN 6.7 is automatically extending this partition when needed, depending on the host requirements. vSAN 6.7 needs larger coredump partition so it is able to automatically resize the coredump partition.

Support for 4Kn Disks – those are a large disk which has a better price per GB than 512e and 512n disks (supported already by the previous version of VMware vSAN). New 4kn disks are supported and the vSAN data plane I/O is optimized for 4Kn.

There is a software emulation for 4Kn.

Improved Security with vSphere FIPS 140-2 validation – VMware VMkernel cryptographic module v1.0 has achieved FIPS 140-2 so vSAN 6.7 takes benefit of this. It uses this FIPS 140-2 validate d cryptographic module implemented already in vSphere.

vSAN 6.7 brings some significant improvements over previous releases and we are really excited about it.

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I am Rahul Sharma, I am currently working as Subject Matter Expert for SDDC and Cloud Infrastructure Services, Mainly on VMware Virtualization Platform.

I have 9 Year’s of IT experience and have expertise in Designing and Deploying of VMware vSphere, vSAN, vCloud Director, vRealize Automation, SRM, NSX  and modern data center technologies like vBlock, Cisco UCS, DELL, HPE C7000, HPE Synergy HCI etc.

I am vExpert, VCIX6-DCV, Dual VCP – DCV & NV, MSCE – Cloud, CCNA, ITIL v3 Certified.

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