Yes, you read that right… this is a post about Citrix XenServer. “What the heck is a VMware fanboy doing writing about Citrix?” That’s a valid question, but I promise there’s a good reason for this Citrix post on a typically VMware centric blog. I’ve recently had to think outside of the box when it comes to virtualization, as my current position as a Sr. Engineer for a federal client has required me to focus on Citrix more than VMware. I came across a weird issue where my entire XenServer would go offline, most likely because of a memory shortage I think, and when it would start back up all the VMs would remain powered off. After reading that, most of you probably knew this was an easy fix, but not for a VMware admin with little Citrix experience. While I had a good idea that we were probably maxing out our memory and it was shutting down the VMs, I still spent a ton of time troubleshooting that possibility instead of first making sure the VMs could stay online or come back up automatically.
The Fix
It turns out, this is a pretty easy fix, and one that should probably be configured on any server running XenServer. Now, stay with me, realize that this is a VMware admin making his first attempt at a Citrix related blog post. I thought someone else would find it helpful, so here are the steps.
1. First you need to log into your XenServer by KVM in the server room or via ssh, I use a Mac, so I just opened up my terminal app and used the command (see the screenshot below):
2. Next you’ll enter your password at the prompt and it will may ask you if you want to continue if you have an invalid security certificate, otherwise it will give you the XenServer prompt. From this XenServer prompt you will first need to set your XenServer to allow auto-start by typing the command “xe pool-list” which will give you your UUID for your VM pool (see screenshot below).
3. Now that you have your VM pool UUID (it’s the string of letters/numbers , you’ll want to grab it and use it in the following command, replacing UUID with your actual pool’s UUID, then hit enter.
4. After you’ve set your XenServer pool to allow auto-start, next you’ll want to select the VMs that you want auto-start enabled on. Now, this part seems silly to me, why isn’t this just an option you can select? Apparently Citrix disabled auto in XenServer 6.x, because it messed with High Availability (HA) and kicked out some weird results during HA procedures. You’ll need to grab the UUID for each VM that you want to enable auto-start on, so start by running the command “xe vm-list” to get a list of all your VMs and their UUIDs. Then you can type the command in the screenshot below to enable auto-start on that VM. Again, remember to replace your VM’s UUID where it says UUID in the command below.
That’s all you need, your VMs will now automatically start-up in the event that your XenServer powers off inadvertently or there’s a power outage in your server room (both things that have happened to me).
Disclaimer: This post is mainly applicable for XenServer 6.0, 6.0.2, 6.1.0, 6.2.0
