VSAN Part 14 – Host Memory Requirements

For those of you participating in the VMware Virtual SAN (VSAN) beta, this is a reminder that there is a VSAN Design & Sizing Guide available on the community forum. It is part of the Virtual SAN (VSAN) Proof of Concept (POC) Kit, and can be found by clicking this link here. The guide has recently been updated to include some Host Memory Requirements as we got this query from a number of customers participating in the beta. The actual host memory requirement directly related to the number of physical disks in the host and the number of disk groups…

VSAN Part 13 – Examining the .vswp object

I’ve seen a few question recently around the .vswp file on virtual machines. The .vswp or VM swap is one of the objects that go to make up the set of virtual machine objects on the VSAN datastore, along with the VM Home namespace, VMDKs and snapshot delta. The reason for the question is that people do not see the .vswp file represented in the list of virtual machine objects in the UI. The follow-on question inevitably is then around how do you see the policy and resource consumption of a virtual machine’s .vswp object.

VSAN Part 12 – SPBM extensions in RVC

In the Virtual SAN (VSAN) beta refresh, we released a number of new Ruby vSphere Console (RVC) commands to examine the Storage Policy Based Management (SPBM) settings. For those of you who have been participating in the beta, you will know that to deploy a virtual machine on VSAN, you create a storage policy for the virtual machine, which may stipulate the number of mirror copies of the virtual machine disk (FailuresToTolerate) or indeed a stripe width for the VMDK. SPBM is the underlying technology which controls this aspect of VSAN. In this post, we can look at some of…

VSAN Part 11 – Shutting down the VSAN cluster

In a post on the vSphere blog, I spoke about how to use maintenance mode. As a follow on request, a number of people asked me how they should safely shutdown a VSAN cluster. In this post, I will address that question and share my observations. On my three-node VSAN cluster, I had a number of virtual machines as well as a vApp running vCenter Operations Manager VMs. My first step was to shut down all virtual machines in my cluster.

VSAN Part 10 – Changing VM Storage Policy on-the-fly

This is quite a unique aspect of VSAN, and plays directly into what I believe to be one of the crucial factors of software defined storage. Its probably easier to use an example to explain the concept of how being able to change storage policies on the fly is such a cool feature. Let’s take a scenario where an administrator has deployed a VM with the default VM storage policy, which is that the VM Storage objects should have no disk striping and should tolerate one failure.The layout of the VM could look something like this: The admin then notices…

VSAN Part 9 – Host Failure Scenarios & vSphere HA Interop

In this next post, I will examine some failure scenarios. I will concentrate of ESXi host failures, but suffice to say that a disk or network failure can also have consequences for  virtual machines running on VSAN. There are two host failure scenarios highlighted below which can impact a virtual machine running on VSAN: An ESXi host, on which the VM is not running but has some of its storage objects, suffers a failure An ESXi host, on which the VM is running, suffers a failure Let’s look at these failures in more detail.

VSAN Part 8 – The role of the SSD

I will start with a caveat. The plan is to support both Solid State Disks and PCIe flash devices on VSAN. However, for the purposes of this post, I will refer to this flash resource as an SSD for simplicity. SSDs serve two purposes in VSAN. They act as both a read cache and a write buffer. This dramatically improves the performance of virtual machines running on the vsanDatastore. In some respects VSAN can be compared to a number of ‘hybrid’ storage solutions in the market, which also use a combination of SSD & HDD to boost the performance of…