Posts made by Martín Lorente

I'm asking because I need to increase my pool's CPU resources, the easy way is buy the same processor, but thinking in a more powerful option, RAM and networking features are ok, but compute performance is being starvest by some VM.

I have an old pool, which I had to upgrade some years ago, but no more original model components were available, so I had to buy a new model, new cpu generation, so it became an heterogenous pool. The problem was not the lost of new cpu features, the problem is that time to time, when I performe a live migration VM, it hangs and I must reboot the VM.

Keeping in mind to avoid and heterogeneus pool, I think the safest option is 5220S, because 6226R implies more changes which I unknow in the architecture, maybe new features, that's what I unknow.

Any piece of advice?

I think no, but I'm wondering your opinions.

In my pool I have 5 server with double intel 5217 (8C 3GHz) processors, I'detected that CPU start to be very higth , so thinking in more powefull CPU. Model 5220S is 18C cores at a similar speed. Both, 5220S and 5217 are gold series of "cascade lake" architecture. So, features must be the same, only cores and speed differ. Intel 6226R is another interesting option, quite similar speed and doubles chip cores.

According to citrix, "Combining different CPU models that have identical features" is the 4th type of heterogeneous pool, and "Type 4 represents CPUs with different marketing model names but identical model number, family, and feature flag attributes. Because they have identical attributes, these combinations have always been supported and do not require a mask, but their compatibility has not been obvious when comparing the marketing model names."

Do you think these chips (5220s and 6226R) would mean an heterogeneous pool or not?

In other words, you must empty the host before add it to the primary pool, of course, you can migrate VM from one pool to another. And if your hw is not the same, but similar, you'll have an heterogeneous pool.

5% sounds too much for me, but I'll check it in some populated pools (with host's cpu below 80%) to have a better idea.

Maybe somebody could point some metrics to predict future cpu/Network overcommit.

As always, reading you expands my knowledge. point 1, perfect, as I thought it was. Point 2, I thought dom0 talk to xen hypervisor by XAPI, thanks for your correction, I supposse dom0 is the only one that can communicate with xen and xcp-ng xencenter or XO use dom0 via XAPI, beeing dom0 who finally passes the order to xen. Point 3, that's what I want, observe parameters like wait and st from top command to detect bottleneck or overloaded resources, like CPU or SR access.

And going back to my original question, what st values should be allowed?. for instance, 20% must indicate a serious lack os resources in the VM.

Anrother wrong concept here for me or I've explained myself wrong. Xen is the hypervisor, is not dom0 a hidden vm where you connect when ssh to the host?, where xe commands are played and the one who controls the rest of the VM running on the same host? Like xencenter, xcp-ng center or XO, dom0 is a way to give orders and get states to/from xen hypervisor via XenAPI.
For instance, start or shutdown any VM is a order that dom0 gives to xen hypervisor, or at least it's what I've always understood.

When I said that I was looking in top, I mean the top command in the VM, not the dom0

Hi everyone.
As far as I'm concerned, the st parameter or steal time is the % of cpu the hypervisor (Domu0) steal from the VM, because it can't supply enough time slots due to a overcommited host. When the host is empty and has plenty of resources, it may give as much cpu time as asked.
I don't know if DomU0 works in extrict or best effort mode, giving just the resources aplied or even more when plenty of resources.

My question is, keeping in mind that hypervisors are not ideal, what % of st is allowable when the host is relaxed?, because I observe st values below 1% in a VM on am empty host.

I'm going to populate the host in next days, and a bit worried about not overcommit it, so I'll be watching this parameter.

As always, if I'm wrong in some point, please correct me.

Well, for me was not clear untill your current answer. As you can see, my conclussions were wrong, but that was just a suggestion.

Could I suggest to update https://xen-orchestra.com/blog/xen-virtualization-modes/ with your answer as the current state-of-the-art?
Do you want me to post my question to get your answer? It's clear for me now.

Another solved post

Regards

So, if I've undertood you well, the mode to get the best performance is HVM, which gets PVHVM under Linux VM when tools/management agent is installed (the drivers are currently in the kernel) and gets PVHVM after install PV drivers and management agent on Windows OS. Rigth?

Hello everyone,
After googling aboit it to refresh concepts, I've ended up confused, coul anybody correct me?

In short:
PV : The best to emulate when no hw assisted exists (really old proccesors). Need kernel modification, no problem for linux.
HVM: When HW help virtualization, present in nowadays proccessors. No Need kernel modification and allow SO act over real HW
PVHVM: The best of both worlds, PV improves it's performance helped by HW assistance
PVH: This concept is new for me, and accordding to this post of Oliver, there 2 versions, v1 and v2.
After read the post, the conclusion for xcp-ng is that when I see a VM working in PV mode , it's indeed PVHv1 and when I see HVM we are really talking about PVHv2. Am I wrong? pv, hvm and pvhvm are no longer in use under xcp-ng, right?

An finally, must Windows VM work in HVM or PV?, Because I undertand that HVM is the best way, but citrix tools refers as PV drivers, not HVM drivers.

P.S. I moved the most of my VMs to HVM when specter and meltdown vulnerabilities.

As always, thanks in advance for your time.

Everything clear.
Thanks.

Thanks for your reply, everything clear, I didn't catch it, beeing in the same website I though some kind of special license for XO over XCP-NG and didn't think it was a quote for xcp-ng hypervisor support. Just a couple of questins more, is XO flat price for one pool (any number of hosts in it) or for any number of pools (any number of hosts in each one)?, because I've already have 6 pools, 4 of them only 2 host members each and the others 2 pools are 5 and 6 host members respectively.
Finally, my hardware is 4 years old in some pools, and is not officialy supported in xcp-ng, but working anyway, for instance lenovo x240M5, is this a problem to purchase XO or XCP-NG support?, not beeing a supported HW, I suppose is not possible for XCP-NG, but XO works over XEN API, which is supported depending on the SW version, not HW, but SW is supported depending a HW, so not sure if it's possible to pay for a support in this situation.

Thanks again

Hi everyone, I was comparing XO versions, from free to premium and have some doubts. I'm not the person who must ask for a quote but the one who point which version ask for, so my question is. where is the diference between enterprise, premium, xcpng-standard and xcpng-enterprise?, the producto matrix doesn't show xcpng licences features.
Secondly, if the prices for starter, stantard and premiun are on the web, ¿why ask for a quote?, ¿any kinf of disccount?

Thanks in advance

I don't know how to mark this post as solved. Must be done by web administrators?

Incredible, the nameserver was 192.168.100.254, something unreacheable from my network. Now it's registered. I realiced performing a xoa check as you suggested. It still says /etc/xo-server/config.yaml doesn't exist, but it's registered and upgrading.
As I said previously, something silly was blocking the registration.

Thanks a lot

I'm trying the same user/password, I've even logout and login again in the website to retype user and passwd and check it. On the web it works, but not in the XOA registration proccess, by the way, Shouldn't be a different message if the user/passwd is wrong?

Hello everibody, it's probably something easy, but I can't aachieve it.
Some time ago I download and import a XOA VM to try XO, but I've been unable to register it, every time y try, I get the same error:

16/6/2020 8:50:31: unknown error from the peer
16/6/2020 8:50:48: Start updating...
16/6/2020 8:50:48: Your appliance is not registered, take time to register first.
16/6/2020 8:50:58: Start updating...
16/6/2020 8:50:58: Your appliance is not registered, take time to register first.
16/6/2020 8:59:32: unknown error from the peer
16/6/2020 9:31:18: Lost connection with xoa-updater
16/6/2020 9:31:18: xoa-updater could not be reached
16/6/2020 9:45:26: Start updating...
16/6/2020 9:45:26: Your appliance is not registered, take time to register first.

A ping beetwen the Vm and XO servers is ok, and no proxy in the middle. I use the same user and passwd that is register in XO web. ¿Any idea?

Thanks in advance.