Accedentally set up a pool on an xcp-ng server

jensolsson.se

Hi

I accidentally set up a pool on one of my xcp-ng servers. Dont know how, maybe there is a question during installation? The pool is named the same as the host.

I have no use for pools so I would actually like to remove it, but since I added a VM to the pool I am affraid if I remove the pool, I will also lose the VM.

Is there any way to keep the VM while removing the pool?

Kind regards
Jens

Danp

@jensolsson-se You didn't do anything wrong. Every server is in a pool, even a lone server.

olivierlambert

As @Danp said, there's always a pool. A "lone host" doesn't exist.

jensolsson.se

OK, makes total sense, I think what confuses me is actually in XCP-ng center where it seem like an extra subtree for the server I installed. to me it seems something is very different with that host.
Please see the screenshot. Why is it xcp-ng-3 -> xcp-ng-3 -> XOA
Whereas I have for example xcp-ng-1 -> XOA and xcp-ng-2 -> XOA ?

Kind regards
Jens

olivierlambert

That's exactly the problem of XCP-ng Center: it's confusing. That's also the reason we really want people to dump it (see https://xcp-ng.org/docs/management.html it's only community maintained)

jensolsson.se

@olivierlambert OK oliver, I pretty much only use XO. But it happens that I log on using XCP-ng Center from time to time, mainly if I want to see if there is some feature that is not in XO.

So you are saying I can pretty much ignore this unusual look of my xcp-ng-3 server?

olivierlambert

It's fine. The only confusing thing is coming from XCP-ng Center. You can rename the pool if you like (regardless where, could be done in XCP-ng Center or XO, or even xe).

churchers

@olivierlambert
Oh no, I really like it coming from XEN.
it should always be there....

jensolsson.se

Thanks for clarifying

Jens

DannieRothmann

Just for absolute clarification:

When a server is added in XCP-ng Center or Citrix XenCenter, it IS stand alone, we have many of these in production - not a problem.
You have to create a pool or add it to an existing pool, to make it a member, so the xcp-.ng-3 is no longer a stand alone server, it is the master of a pool called xcp-ng-3 - not a problem.
To remove it from the pool again - BIG problem, because you can not remove the master from a pool. You can destroy the pool by "hacking" and you will loose all VM's on local storage ! - BAD IDEA
Leaving it as is looks a little strange, but has absolutely NO impact on the servers functionallity or reliabillity.
So either "backup VM, reinstall server, do not create a pool and restore vm" OR Just live with it as is

stormi

@dannierothmann This is not entirely accurate. As we said earlier, any host, right from the start, is always included in a pool of its own. Just run xe pool-list on it and you'll see. But XCP-ng Center apparently hides this fact so that you'd see it as a standalone host, unless you tell it "I want a pool".

You could check in XO, which reflects the exact state of things in the XAPI database: any host belongs to a pool. Always.

DannieRothmann

@stormi
Ok, I stand corrected, but then its not only a XCP/Xencenter issue. xsconsole also clearly differentiates between being member of a pool or not ? I know that there is always a "master", but either of a stand alone server or of a pool.

I actually think that this is one of these situations that totally frustrates a trainer, where what the trainer see in all official training materials (Citrix) and what you actually see in the source code.

@stormi you know the code far better than me, so when you say it

I will rephrase:
Even though it looks like there is a difference in both XCP/Xencenter and xsconsole, there is actually no difference in the actual system behind the interfaces.
As long as you work with XCP/XS consoles, my previous comment is what you see and experience when using these unsupported tools !
If you use the servers for production, there is only ONE tool you can rely on .... Xen Orchestra .... (and the support is outstanding)

stormi

@dannierothmann About xsconsole (which is supported), where do you see a difference between "in a pool" and "not in a pool"?

DannieRothmann

@stormi
Standalone:

Single server (New pool created):

stormi

Thanks. So there must be a difference somewhere in database or on the host itself. I suspect the only goal behind this was to make believe the host isn't in a pool in order to not confuse users who'd expect that no pool exists when there's only one host... And the result is it's still confusing because now we can have two different setups that are completely identical except that one claims there's no pool and the other says there is

I suppose /etc/xensource/pool.conf contains master in both cases? That's what I see here.

DannieRothmann

@stormi

I agree, confusing.

Would be easier the Starwars way:
"Always two, there are. No more. No less. A Master and a pool"

olivierlambert

There's no diff. It's just that if you pool doesn't have a namelabel, XenCenter and xsconsole will detect that and tell you it's not in a pool. It's just a plain lie.

olivierlambert

@dannierothmann

jensolsson.se

@olivierlambert Interesting is it possible to simply remove the namelabel. I know it does not matter but I think it is nice to do the same on all hosts

stormi

@jensolsson-se I'd try with xe pool-param-set [...]. Find the appropriate param name with xe pool-param-list. Disclaimer: I did not check if it's possible.