@CodeMercenary Thanks for providing this. My fans suddenly spun up like crazy and I used that github container to calm them down. Works a treat!

That package installs a container that runs every X seconds and connects to the server and resets the fans. I don't find that necessary. In fact, my fans went nuts after I installed a 3rd party (non-Dell) SAS controller. I notice that one of the IPMI parameters it sets is THIRD_PARTY_PCIE_CARD_COOLING_RESPONSE. I set that to false. It hasn't spun the fans up super high. I think setting that once was persistent and there's no need to have this script connecting every so often resetting the fans.

If anyone is looking for a one-time fix to this, I think running this command one time is sufficient.

@Danp As soon as I read that, I thought "I think I've been down this road before." Sure enough. I gave it 2G of RAM and it wouldn't build. I gave it 4G of RAM and I watched using systat and that final step went to about 52% of RAM usage. It has completed. I routinely run Xen Orchestra on a 1G VM because it's rarely used and it runs fine that way. But building it clearly takes a lot more RAM. I'll update my internal notes. It might be worth it to update the building from source docs to mention having enough RAM.

Thanks for hitting the nail on the head with that advice!

@olivierlambert You expect a system administrator to read documentation!?

Anyways, that was it. Sorry I didn't look more carefully. I rebuilt using node8 and poof it was running. Thanks guys.

I'm willing to contribute some documentation on templates, because I keep looking up how to work with them. Every so often another person posts some basic questions about them, and there isn't one central place to send them.

What I wanted to do was collect the basics of what I know here in this thread, and give people an opportunity to add other things they think should be in a documentation page on templates, and then I'll go write the page and contribute it to the docs.

My thinking is to organize it around "CRUD": Create, Read, Update, Delete.

Create

There's basically 3 ways to create templates.

1. From an existing VM. For example, you can install Linux or FreeBSD or whatever on your VM at some basic level with a few customizations, and then make a template from that.
2. Duplicate one of the default templates and then modify it (subject to the limitations in "Update" below)
3. Create a VM, then convert it to a template. The only difference between this and #1 above is that if you never boot it or install any OS, you create a template that has an unformatted disk. This just gives you customized RAM, CPU and other values. See the section on "Delete" where I talk about diskless templates. Am I understanding it right?

Any other useful ways to create that I haven't mentioned?

Read

How can I see the properties of a template in Xen Orchestra? If I click the hamburger menu, all I can see are tags, CPU and RAM. If I want to see other values, it seems like I have to start to create a VM, choose the template, and then click on the "Advanced Settings" to see what the template sets them to.

Pull from the API? This forum post mentions that. Is that this documentation on the xo command or something else? What should I link to for more information on invoking the API?

From the CLI you can get all the information from a template. If I've created a template called My Debian Template, this is how to see its values.

xe template-list name-label="My Debian Template"
uuid=$(xe template-list name-label="My Debian Template" --minimal)
xe template-param-list uuid=$uuid | less

Update

I can't find a way in Xen Orchestra to modify the parameters of a template. There's a thread here that talks about finding it, clicking the hamburger menu, then editing the values. When I do that, I see a little green check mark next to the value I changed, but the values don't actually change. Is this meant to work? And those are really basic settings. What about changing advanced settings in Xen Orchestra?

I guess there's a cumbersome way to modify a template in XO: I could create a VM from my template, modifying the values to what I want them to be, and then convert that VM to a new template. Then I delete the old template? Does that work?

The only way I have found to update a template is to set values from the command line following this post. For example (assuming $uuid is set from my prior example) this will set memory-static-min to 512Mb.

xe template-param-set memory-static-min=$((1024 * 1024 * 512)) uuid=$uuid

Any other ways to update the properties of an existing template?

Delete

It seems simple enough to find a template in Xen Orchestra, select the box next to it, and click the trash can. According to this post, that will leave orphan VDIs that have to be deleted manually. But this is not true of the default templates, right? So:

1. Deleting a default template: you just find it in the GUI and delete it.
2. Deleting a custom template you created: you need to do the steps in that post: find the drives, delete them, then delete the template?

This also leads me to ask whether it's possible to create a template like the default templates, where there's no associated disk? I guess you just create a VM without a disk and turn that into a template?

Also, you can delete the default templates, but they get re-installed again during a major version upgrade, right? So you either live with them, or you have to delete them again after every major upgrade?

Cloud-init and Cloudbase-Init

There's some useful docs on cloud-init and cloudbase-init that could move to this page if we have a whole page devoted to working with templates.

Thoughts?

What Am I Missing?

This is as much as I know right now. Anything else we should add to docs on templates?

In case anyone wonders how this played out. At the end of the day, I shutdown the host with the running workloads on it, kept it at BIOS boot so the 8.3 installer would upgrade it cleanly, and then booted it back up. For reasons related to my particular setup, the down time was more than 60 minutes. But that's not related to XCP-ng. The XCP-ng installer was maybe 10 of that. 20 of that was 3 reboots on a server that takes ages to boot.

One thing that is a bit difficult is that the 8.3 installer doesn't notice ZFS volumes or help with ZFS. So after the upgrade, I have to follow a modified set of these instructions (modified because the package names have changed over time) to install ZFS and its components into the system. So the sequence is:

1. Shutdown
2. Install via ISO
3. Reboot to single user mode
4. Run yum update to pull in all the updates
5. Run the ZFS commands to install ZFS on the host
6. Reboot again
7. Run normally

Of course, I ended up rebooting more than just those 2 times, because I forgot that I would need to install ZFS (even though I did it on 2 different hosts already )

So now the pool is fully upgraded, everybody is happy. I'm now working on creating shared storage across the nodes. It's amateur hour over here. I appreciate all the help.

@stormi Thanks. I appreciate it. But unfortunately, I'm unable to move workloads off the master in order to take it offline because of this situation.

If the solution is to turn off a host while it has live workloads, then I'm just going to shutdown the 8.2.1 slave and upgrade it to 8.3. Then I have 2 members in the pool and it's fully upgraded.

Let me tell you another edge case I encountered. There are some clear mistakes in here that I made, but it is related to this issue. When I took C offline and upgraded it to 8.3, I took the opportunity to convert it to UEFI boot. That meant reformatting the boot drive, not upgrading it. I wasn't worried about that. I took it out of the pool, reformatted it, and created a one-node 8.3 pool that has just node C in it. No biggie, right? I'll just have it join the pool with the 8.3 master and all is well. No, that's not going to work. Can I at least move some workloads onto it? Nope.

When you do a fresh install, pool-enable-certificate-verification defaults to yes. When you upgrade a pool, pool-enable-certificate-verification defaults to no. So I have a half-upgraded pool with 2 nodes with certificate verification disabled, and a single-node 8.3 pool with certificate verification enabled.

If I try to enable certificate verification on my half-upgraded pool? Our good friend NOT_SUPPORTED_DURING_UPGRADE() comes back to say "hi". As far as I can tell, it is not possible to disable certificate verification on the single-node 8.3 pool.

So I have a one-node pool where I can't turn verification off and a 2-node, half-upgraded pool where I can't turn it on. That makes it really difficult for the two pools to interoperate.

If I have to be known for something, let me be known as a cautionary tale.

@julien-f Yeah, I have just found the useSudo option in the docs. I swear things change fast enough on xen orchestra that "upgrading" almost doesn't make sense. I rebuild it like every 3-6 months and so much changes that it's almost easier to start over. If I had started over and pretended I didn't know anything, I would have read the documentation and seen the useSudo option. That's not a complaint. Fast development and adding features is awesome.