Wednesday, August 31, 2016

#VMworld Architecting VSAN the VCDXway @simonlong_ & @rayheffer

Great Session presented by Simon Long and Ray Heffer. Before getting into VSAN you need to understand some basic terms:
  1. FTT - Failures to Tolerate - How many hosts needed to tolerate failures
  2. Flash Read Cache Reservation - SSD capacity reserved as read cache for the virtual machine object
  3. Object Space Reservation - the reserve specified as a percentage of the total object address space
  4. Failure Tolerance Method - can be set to either performance or capacity
  5. Witness - ESXi host used for tie breaking
  6. Sparse Swap - provisions VM without space reservation for VM swap
VSAN Objects are all files that make up a VM such as the VMDK and snapfile. When an object is deployed on VSAN it will have related items distributed across hosts. These related items are referred to as Components and are the building blocks of all Objects.

In addition you have SAN Disk Groups that are used to pool flash and magnetic disks. Disks groups are composed of 1 cache disk and at least 1 capacity disk.

VSAN supports View Storage Accelerator. View Storage Accelerator stores commonly used read blocks in DRAM on the ESXi hosts. The Minimum number of Hosts is for VSAN is 2 while the maximum is 64. 2 does not include the witness host. There is a branch architecture that can be done with a 2 host configuration with the witness located elsewhere. VSAN does not support SIOC, Storage DRS or SE Sparse Disk.

When integrating Horizon it will automatically create different VSAN Storage policies based on the Desktop Pool type deployed. If you manually change the Storage policies then a Refresh, Recompose or Rebalance will switch them back to the defaults.

There are 6 default VSAN Storage Policies such as Dedicated Linked Clone, Floating Full Clone, Replica and Persistent Disk that are created by Horizon. It is a good idea to change the FTT setting for the Replica Policy to 2. Is is also a good idea to create a Golden Master VM and Default SAN policy as well.

When you are building out a Horizon environment it is important to understand the business requirements as well as the constraints. In addition use should look to remove all your Single Points of Failures "SPOF" in your design.

While you can deploy View on a Virtual SAN Stretched Cluster, you do have to be careful as the java connection service communication between Connection servers is not latency tolerant. It may be better to have separate View Pods using version Horizon 7 vs. a single Pod depending on the latency between datacenters.

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