Some time ago, I wrote about which policy changes can trigger a rebuild of an object. This came up again recently, as it was something that Duncan and I covered in our VMworld 2017 session on top 10 vSAN considerations. In the original post (which is over 3 years old now), I highlighted items like increasing the stripe width, growing the read cache reservation (relevant only to hybrid vSAN) and changing FTT when the read cache reservation is non-zero (again only relevant to hybrid vSAN) which led to a rebuild of the object (or components within the object). The other…
Regular readers will be aware that I “dabble” from time to time in the world of Cloud Native Apps. For me, a lot of this dabbling is trying to figure out how I can go about providing persistent storage to container based applications. Typically this in the shape of container volumes that are carved out of the underlying storage infrastructure, whether that is VMFS, NFS, vSAN or even Virtual Volumes. VMware Project Hatchway has enabled me to do this on multiple occasions. Project Hatchway was officially announced at VMworld 2017, but I’ve been working with this team since the early…
It seems that 2-node vSAN for ROBO (remote office/branch office) deployments are becoming more and more popular. The fact that one can now connect the 2 vSAN hosts at the remote office directly back-to-back without needing a 10Gb switch has reduced the cost extensively. And with the introduction of a vSAN Enterprise for ROBO license edition with vSAN 6.6.1, you get the full feature set of vSAN on 2-node deployments. This new edition builds on the vSAN Advanced edition, and enables the use of features like native encryption and stretched clusters on a per-VM pricing model for smaller sites. The…
During one of our many discussions at VMworld 2017, I was asked about supporting Fault Tolerance on vSAN Stretched Clusters, more specifically SMP-FT. Now to be clear, we can support SMP-FT on vSAN since version 6.1. The difficulty with supporting SMP-FT on vSAN stretched cluster has always been the possible latency between the data sites, which could be up to as much as 5ms. This is far too high to support SMP-FT on a VM that has data replicating between data sites, and for that reason, we stated categorically that we could not support SMP-FT on VMs deployed on vSAN…
Many of you who are well versed in vSAN will realize that we released a Secondary Failures To Tolerate (SFTT) feature with vSAN 6.6. This meant that not only could we tolerate failures across sites, but that we could also add another layer of redundancy to each copy of the data maintained at each of the data sites. Of course the cross site replication (now referred to as PFTT or Primary Failures To Tolerate) is still based on RAID-1 mirroring and this continues to require a third site for the witness appliance, so that quorum can be obtained in the…
The last of my VMworld 2017 sessions is now available for viewing. This is the vSAN Networking session, which I co-presented with Andreas Scherr. Andreas is responsible for taking care of all of our vSAN proof-of-concept deployments in EMEA. In this session we cover many aspects of vSAN networking design and configuration, such as NIC teaming, load balancing, supported topologies, and so on. The session includes some very interesting demos, highlighting what can go wrong when the networking is not optimal. Hope you like it, and feedback is always welcome.
After publishing the vSAN Networking Guide earlier this year, Paudie O’Riordain and I received numerous questions regarding support on having different stretched clusters hosting each other’s witness appliances. These queries arose because we discussed a 2-node (ROBO) topology which allowed this to sort of configuration (i.e. the cross hosting of witnesses) via special request. But in the networking guide, we explicitly stated that this was not supported with vSAN stretched clusters. However, after some further testing by our engineering teams, we can now relax this restriction if there are 4 independent sites hosting the different stretched clusters. In this case,…