Yellow Bricks

by Duncan Epping

vsan file service

vSAN File Services: Seeing an imbalance between protocol stack containers and FS VMs

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Last week I had this question around vSAN File Services and an imbalance between protocol stack containers and FS VMs. I personally had witnessed the same thing and wasn’t even sure what to expect. So what does this even mean, an imbalance? Well as I have already explained, every host in a vSAN Cluster which has vSAN File Services enabled will have a File Services VM. Within these VMs you will have protocol stack containers running, up to a maximum of 8 protocol stack containers per cluster. Just look at the diagram below.

Now this means that if you have 8 hosts, or less, in your cluster that by default every FS VM in your cluster will have a protocol stack container running. But what happens when you go into maintenance mode? When you go into maintenance mode the protocol stack container moves to a different FS VM, so you end up in a situation where you will have 2 (or more even) protocol stack containers running within 1 FS VM. That is the imbalance I just mentioned. More than 1 protocol stack container per FS VM, while you have an FS VM with 0 protocol stack containers. If you look at the below screenshot, I have 6 protocol stack containers, but as you can see we have the bottom two on the same ESXi host, and there’s no protocol stack container on host “dell-f”.

How do you even this out? Well, it is simple, it takes some time. vSAN File Services will look at your distribution of protocol stack containers every 30 minutes. Do mind, it will take the number of file shares associated with the protocol stack containers into consideration. If you have 0 file shares associated with a protocol stack container then vSAN isn’t going to bother balancing it, as there’s no point at that stage. However, if you have a number of shares and each protocol stack container owns one, or more, shares than balancing will happen automatically. Which is what I witness in my lab. Within 30 minutes I saw the situation changing as shown in the screenshot below, a nice evenly balanced file services environment! (Protocol stack container ending with .215 moved to host “dell-f”.)

Enabling vSAN File Services in a vSAN cluster larger than 8 hosts

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I noticed something over the weekend, and I want to make sure customers do not run in to this problem. If you have more than 8 hosts in your vSAN Cluster and enable vSAN File Services than the H5 client will ask your for more than 8 IP addresses. These IP addresses are used by the protocol stack containers. However, as described in this post, vSAN File Services will only ever instantiated 8 protocol stack containers in the current release. So do not provide more than 8 IPs, I tried it, and I also ran in to the scenario where vSAN File Services was not configured completely and properly as a result. You can simply click the “x” as pointed out in the screenshot below to remove the IP address entry line(s) to work around this issue. Hopefully it will be fixed soon in the UI.

vSAN FS: Existing domain information has been pre-populated below

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I have been playing with vSAN File Services a lot the past couple of weeks. I have been configuration and re-configuring it a few times. At some point, I found myself in the situation where when I wanted to enable vSAN File Services and provide new IP details that I received the following error: “Existing domain information has been pre-populated below”. shown in the below screenshot.

Why did this happen? Well, the configuration details are stored in the objects that form the file shares. I disabled vSAN File Services while I still had file shares running. This then results in the scenario where when you enable vSAN File Services that it detects the file share objects, it will read the configuration details and assume that you will want to configure it with the same Domain/Network details so that you can access the existing shares. But what if you don’t? What if you want a brand new shiny environment? Well, that is also possible and you can do that as following:

  • Enable vSAN File Services with existing domain information
  • When configured, go to File Service Shares and delete all existing file shares
  • When all are deleted, disable vSAN File Services
  • When all tasks are complete, enable vSAN File Services again
  • Enter new Domain and Networking details

Pretty simple right?

vSAN File Services considerations

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I was looking into vSAN File Services this week as I had some customers asking about requirements and constraints. I wanted to list some of the things to understand about vSAN File Service as it is important when you are designing and configuring it. First of all, it is good to have an understanding of the implementation, well at least somewhat as vSAN File Services is managed/upgraded/update as part of vSAN. It is not an entity you as an admin, don’t manage the appliance you see deployed. I created a quick demo about vSAN File Services, which you can find here.

If you look at the diagram (borrowed from the VMware documentation) above, you can see that vSAN File Service leverages Agent/Appliance VMs and within each Agent VM a container, or “protocol stack”, is running. The protocol stack exposes the file system as an NFS file share. [Read more…] about vSAN File Services considerations