Also curious what the use case of this is.
The only genuine use case I can think of for this is for a basic Storage Repository containing ISOs for VMs so they can spin up.
Or are you expecting an AWS S3 equivalent or Windows File Explorer equivalent?
Thanks @lawrencesystems - I've finally got around to watching that video, explains the content well, quite interesting to see that happening in real time when the RAM is being land-grabbed by other VMs when things are getting full based on the different configuration settings.
@tjkreidl That sounds like it's answered 99% of initial questions to be fair.
The 1% I'm not clear on is, what would happen in the scenario whereby say I have 10x VMs, which in total took up 100% of RAM for example - but they were all turned off.
Would I still be able to create an 11th VM with 100%+X RAM allocation and still turn it on successfully? i.e. because the other 10VMs are turned off?
From what you've said, I'd come to the conclusion of 'yes'.
Seems easier to have a conversation around the topic rather than me trial and error playing around blindly.
How does this work? I've yet to reach the max CPU + RAM allocation to the VMs on the XCP-ng Server Host, so I'm just thinking ahead.
For each VM, are the CPU and RAM allocations fixed, i.e.
or
or
I'm pretty sure it's #1 from the above out of the box, but just checking.
And if my current understanding is correct, what options are there for over provisioning with the acceptable consideration that performance degradation is likely.
In reality this is for a lab setup, so this is more to over provision to allow more playground VMs as more often than not only a small handful will be turned on at any one time.
Which thinking about this just as I type raises another thought. Is it possible to over provision as long as things are turned off? That's a bit of a second question I guess as both scenarios are valid.
Good old Windows automatic upgrade/reboot/annoying-as-hell-feature has kicked-in.
I've just re-tested this since the above has happened (causing the endless disruptions across everything running on Windows). But anyhow.
Seems to be magically fine now from an XO perspective (I've not done a single thing since this post VS this annoying auto Windows reboot/upgrade);
No idea what this issue could have been caused by, highly likely a weird compatibility issue with a specific Google Chrome version is what I would come to the conclusion of.
Seems like the age old solution in IT has worked again..... Turn it off and back on again 
I've had a few issues over recent years (other technology stacks, nothing related to XCP-ng stuff) where Google Chrome Version X,xx has broken something that should "just work", so I'd add this to the list of items that fall into that category based on this not working then magically working again after a forced reboot + general upgrade etc.
It certainly does explain why I was confused along the way 
Anyhow looks like this is solved.
What a weird issue, nothing related to XO in the end after all. The joys of working in IT/Technology/Software, so many layers inside and outside of control etc.
Interesting.
Chrome with a Dark Mode theme installed;
Edge (default as I don't use);
I can only assume that it's the Dark Mode theme I've installed on Google Chrome getting in the way with things and getting a bit confused.
No wonder why I was getting confused, I couldn't see the thing I was expecting to see, yet it was right in front of my face hiding in plain sight 
@Andrew "You can access the VM console from XO as long as XO has server (not guest) access. It's out of band access to the virtual VGA console."
How would I verify what level of access it has? Is there a page/screen in XO that shows this info?
Very quick insights, thanks all. Great to have an active community.
I've since installed Guest Tools on the VM via XCP-ng Center as it was something I needed to do to process with something.
But before I did this, these buttons weren't allowing me to click them, came up with a stop-sign icon and a message that was saying that I couldn't click them because there was no IP;
If it's nothing obvious from what I've said above, I'll see if I can re-create the exact steps on a new VM to replicate the exact steps I did to get this error error message.
It just raised my eyebrow when I saw the error. As within XCP-ng Centre I'm used to using this tab and seeing a handy console window which allows me to get to the VM command line (i.e. in the case when there is no IP and I can't access via PuTTy) so I can still control the VM to fix anything I have screwed up, such as installing Guest Tools, then I can access via PuTTy from that point forward which is just a better user experience than via the in-built console in XCP-ng Center
I'm trying to replicate all the familiar things I'm used to from XCP-ng Center within XO whilst getting up to speed.
Ok, so I know how to do this. But I'm confused when it comes to XO, let me explain.
Am I missing something obvious? Bit of a catch 22 conundrum.
I'm going to re-test this by repeating Step 1 as I'm not 100% sure which way I did this.
@ronivay I see. I was having a test of resizing the partition and file system the other day and the guide I was following online for Debian 10 didn't seem to do anything when I followed the guide.
Perhaps I just found a bad guide. I'll do some more Googling now I know that I need to perform these additional steps.
I assumed that it was simply a case of expanding the disk attached to the VM within XO/XOA then everything else was taken care of.
Something doesn't seem quite right here.
I originally setup XOA VM via XCP-ng Center. Then I setup XO VM via XOA VM.
Originally XO VM had 40GB Disk Size.
I've tried re-sizing the XO VM Disk via XCP-ng Center and also XOA - but both XO and XOA show 45GB disk size, yet the basic df -h command still shows ~40GB.
Something doesn't seem to be flowing through quite as it should under the hood.
Any ideas while I'm off to investigate to see what could be going on?
Updated to latest commit and that seems to have solved things.
Summary though... I did the old IT solution of turning the server off and back on again, and magically it's working now. How bizarre.
That being said, I've just successfully ran the two backups manually which have worked successfully, but when I click on the 'Disable' button to try to 'Enable' the automated backups, the same error occurs
Same error.
I'm wondering if this could in some how be related to the Backup HDDs currently going through a migration from JBOD to RAID Array which is happening at present. I'll have to wait a few days until I can re-test this once this background process isn't running due to the lengthy time for this happening. I wouldn't have thought that would have caused an issue though as the HBA should take care of all of this under the hood.
Interestingly, the VM backups I've set up previously worked fine.
Yet when I try to create a new VM backup that has worked previously, this is now failing.
Same for when I try to Edit then Save (no changes) to an existing backup, that also now fails. Hmm. May be pointing to a bug in the latest version of XO in that commit.
I'll update to the very latest version at some point over the next few days and give this another test as it may have already been fixed in recent commits, assuming it is a bug and not something weird with my setup.
Backup > New > Backup Metadata > Pool Metadata
Error also when doing
Backup > New > Backup Metadata > XO Config
Create
MISCONF Redis is configured to save RDB snapshots, but it is currently not able to persist on disk. Commands that may modify the data set are disabled, because this instance is configured to report errors during writes if RDB snapshotting fails (stop-writes-on-bgsave-error option). Please check the Redis logs for details about the RDB error.
I can't find any settings in either XO or XCP-ng Center that allows any kind of configuration related to this option.
A Google search turned up virtually nothing XCP-ng related on this topic, so I'm a bit lost.
Any ideas?
@julien-f @marcungeschikts @olivierlambert
Commenting as I feel my recent error (https://xcp-ng.org/forum/post/53557) is somehow related to this thread reading through the comments and history.
cc. @Tristis-Oris
@Tristis-Oris So you did. I must have missed that on the first few reads
I've added this in now so the backup disk has [NOBAK] at the start of the disk name (I've not rebooted the XO VM or full server server yet, not sure it that could be causing an issue), and I'm getting this error which I can't quite figure out yet
Job canceled to protect the VDI chain
I've isolated the XO VM so that it is running now in it's own independent Full Backup to make sure that none of the other VMs are getting tangled up.
I need to have a read up on this error, so just posting this question while I get back to the docs/Google on what this means and how to solve etc.
Lot of assumptions in that The Register write up.
Hobbyists not wanting to pay for licences, running on old hardware, supporting charities, etc. (Paraphrased)
The reality is that any "hobbyist" playing with this kind of tech, it's really a hobbyist. I'm not sure I would class anyone playing with this kind of technology a hobbyist, this suggests a lack of professionalism towards these technologies.
Let's be honest, 95% of people playing with this tech are going to be in some fairly high end jobs and/or high end IT consultancy. No-one has a hobby to use Type 1 Hypervisors, server grade hardware (brand new OR second hand) and commercial grade networking infrastructure required as a baseline to get this set up.
Many people in the IT world have probably never even heard of the concept of a Type 1 Hypervisor, let alone want to get into this well-known "Hobby".
The majority of the community contribute to progress their own understanding from a professional perspective and to pay it forward to support those who are chomping at their heels.
The reality is that for most big corporate enterprise companies (Citrix and many others) is that they often go down the route of providing £x,xxx training courses to learn their tech and expecting organisations to pay for this. Many organisations don't invest heavily in their staff through corporate training programmes. So people are left to find these things out on their own time in many cases.
No individual outside of the corporate working world is going to pay this level of investment for a course that, in my experience (not related to Citrix specifically), often provides little added value beyond a few Google searches, a ton of questions in the community and a watching a few YouTube videos.
There is a big difference in a community of professionals and a community of hobbyists.
If anything, that write up just shows how little they still understand about the community.
@Tristis-Oris At the minute I'm just playing with full backups. The delta backups are next to dig into.
Re. the [NOBAK] tag you mention. No I've not done that. I've not come across any documentation for how to go about implementing this, or even come across the terminology yet. Do you have any handy reference guides that I can take a look at for how to implement that?
I'll do some Googling on this topic in the mean time. It sounds promising.
Re. Zabbix. Where does this fit into the mix. XCP-ng and XO provide a lot of monitoring info out of the box anyhow. I've come across Zabbix and seen it mentioned a few times online, but I've yet to find the time to dig into the details and have a play and understand where it fits architecturally etc.
Physical Disks Setup;
Virtualisation Setup;
Ultimately the backup of the VM with XO installed is failing due to lack of disk space on the RAID Array for Backups.
So I deleted all of the backups on the RAID Array for Backups.
Then re-run the backup job that backs up all VMs. They all worked, with the exception of the VM with XO installed, which failed again due to lack of disk space.
I have a sneaky feeling that the backup of the VM with XO installed is trying to backup the main disk for XO plus the mounted disk for the Backups, hence creating an exponentially growing problem.
I gave this approach a test off the back of this thread, https://xcp-ng.org/forum/topic/6274/backups-to-specific-storage-repository-on-local-possible?_=1664570110880
Is this one of the limitations for this approach? Or have I simply done something dumb and not configured things properly?
cc. @Tristis-Oris as you seem to have worked with this setup before so may have come across the solution to this?
Thanks @olivierlambert that's always good
I'll take you up on that offer probably in about 6 months once I've figured out XO, then I can understand how XO and XOA are different. It's taken me a couple of years to get to this point of understanding with all the supporting knowledge required even before XCP-ng is even installed 