@Biggen At the moment, xcp-ng center provides some better views and overviews not yet available in XO.. Hoping next major version fixes this

@dinhngtu Thank you. I think it is clear for me now.

The docs at https://xcp-ng.org/docs/guests.html#windows could be improved to cover all three options but also to be a little more concise to make it easier to read.

Tested the new updates on my prod EPYC 7402P pool with iperf3. Seems like quite a good uplift

Ubuntu 24.04 VM (6 cores) -> bare metal server (6 cores) over a 2x25Gbit LACP link.

Pre-patch

• iperf3 -P1 : 9.72Gbit/s
• iperf3 -P6 : 14.6GBis/s

Post Patch

• iperf3 -P1 : 11.3GBit/s
• iperf3 -P6 : 24.2GBit/s

Ubuntu 24.04 VM (6 cores) -> Ubuntu 24.04 VM (6 cores) on the same host

Pre Patch

Forgot to test this...

Post Patch

• iperf3 -P1 : 13.7GBit/s
• iperf3 -P6 : 30.8GBit/s
• iperf3 -P24 : 40.4GBit/s

Our servers have Last-Level Cache (LLC) as NUMA Node enabled as most our VMs do not have huge amount of vCPUs assigned. This means for the EPYC 7402P (24c/48t) we have 8 NUMA nodes. We however do not use xl cpupool-numa-split.

Sorry for spamming the thread.

I have two identical servers (srv01 and srv02) with AMD EPYC 7402P 24 Core CPUs. On srv02 I enabled the LLC as NUMA Node.

I've done some quick benchmarks with Sysbench on Ubuntu 20.10 with 12 assigned cores. Command line: sysbench cpu run --threads=12

It would seem that in this test the NUMA option is much faster, 194187 events vs 103769 events. Perhaps I am misunderstanding how sysbench works?

With 7-zip the gain is much less, but still meaningful. A little slower in single-threaded performance but quite a bit faster in multi-threaded mode.

Problem was a stale connection with the NFS server. A reboot of the NFS server fixed the issue.

@xcprocks said in Restoring a downed host ISNT easy:

So, we had a host go down (OS drive failure). No big deal right? According to instructions, just reinstall XCP on a new drive, jump over into XOA and do a metadata restore.

Well, not quite.

First during installation, you really really must not select any of the disks to create an SR as you could potentially wipe out an SR.

Second, you have to do the sr-probe and sr-introduce and pbd-create and pbd-plug to get the SRs back.

Third, you then have to use XOA to restore the metadata which according to the directions is pretty simple looking. According to: https://xen-orchestra.com/docs/metadata_backup.html#performing-a-restore

"To restore one, simply click the blue restore arrow, choose a backup date to restore, and click OK:"

But this isn't quite true. When we did it, the restore threw an error:

"message": "no such object d7b6f090-cd68-9dec-2e00-803fc90c3593",
"name": "XoError",

Panic mode sets in... It can't find the metadata? We try an earlier backup. Same error. We check the backup NFS share--no its there alright.

After a couple of hours scouring the internet and not finding anything, it dawns on us... The object XOA is looking for is the OLD server not a backup directory. It is looking for the server that died and no longer exists. The problem is, when you install the new server, it gets a new ID. But the restore program is looking for the ID of the dead server.

But how do you tell XOA, to copy the metadata over to the new server? It assumes that you want to restore it over an existing server. It does not provide a drop down list to pick where to deploy it.

In an act of desperation, we copied the backup directory to a new location and named it with the ID number of the newly recreated server. Now XOA could restore the metadata and we were able to recover the VMs in the SRs without issue.

This long story is really just a way to highlight the need for better host backup in three ways:

A) The first idea would be to create better instructions. It ain't nowhere as easy as the documentation says it is and it's easy to mess up the first step so bad that you can wipe out the contents of an SR. The documentation should spell this out.

B) The second idea is to add to the metadata backup something that reads the states of SR to PBD mappings and provides/saves a script to restore them. This would ease a lot of the difficulty in the actual restoring of a failed OS after a new OS can be installed.

C) The third idea is provide a dropdown during the restoration of the metadata that allows the user to target a particular machine for the restore operation instead of blindly assuming you want to restore it over a machine that is dead and gone.

I hope this helps out the next person trying to bring a host back from the dead, and I hope it also helps make XOA a better product.

Thanks for a good description of the restore process.

I was wary of the metadata-backup option. It sounds simple and good to have, but as you said it is in no way a comprehensive restore of a pool.

I'd like to add my own oppinion here. A full pool restore, including network, re-attaching SRs and everything else that is needed to quickly get back up and running. Also a restore pool backup should be available on the boot media. It could look for a NFS/CIFS mount or a USB disk with the backup files on. This would avoid things like issues with bonded networks not working.

Might a different solution be to use a USB network bridge instead of direct attached USB? Something like this https://www.seh-technology.com/products/usb-deviceserver/utnserver-pro.html (There are different options available)... We use my-utn-50a with hardware USB keys and it has shown to be very reliable over the years.

I re-checked again but the issue is unfortunately not resolved. It does not happen on all VMs and files, so maybe there is something wrong somehow in the VDI?

@McHenry

Looks like you want disaster recovery option. It creates a ready-to-use VM on a separate XCP-ng server. If your main server fails you can start the vm directly off the second server.

In any case, backups can be restored with XO to any server and storage available in XCP-ng.

@rtjdamen you could simply make two backup jobs, one for daily backups and one for monthly backups.

@mdavico said in Debian 9 virtual machine does not start in xcp-ng 8.3:

Update: If I change the vCPU configuration to 1 socket with 4 cores per socket the VM starts correctly

Interesring. First time I heard it had any effect at all on a VM.

Tested the new updates on my prod EPYC 7402P pool with iperf3. Seems like quite a good uplift

Ubuntu 24.04 VM (6 cores) -> bare metal server (6 cores) over a 2x25Gbit LACP link.

Pre-patch

• iperf3 -P1 : 9.72Gbit/s
• iperf3 -P6 : 14.6GBis/s

Post Patch

• iperf3 -P1 : 11.3GBit/s
• iperf3 -P6 : 24.2GBit/s

Ubuntu 24.04 VM (6 cores) -> Ubuntu 24.04 VM (6 cores) on the same host

Pre Patch

Forgot to test this...

Post Patch

• iperf3 -P1 : 13.7GBit/s
• iperf3 -P6 : 30.8GBit/s
• iperf3 -P24 : 40.4GBit/s

Our servers have Last-Level Cache (LLC) as NUMA Node enabled as most our VMs do not have huge amount of vCPUs assigned. This means for the EPYC 7402P (24c/48t) we have 8 NUMA nodes. We however do not use xl cpupool-numa-split.

@CodeMercenary,

It is a good suggestion. I have asked for similar in the past too I think having retetion periods like that is very good practice.

I have tried to do something similar by creating multiple backup jobs and assigning tags to them.

It is not perfect, but it is easy to determine what jobs specific VMs belong to. I would love to be able to create a progressive schedule like in your example, as well as being able to create one-off snapshots and backups that stay outside the normal schedules.

@olivierlambert said in NVMe SSD not found when installing:

@DustinB Last time I checked, VMD is a shitting half-baked soft/hard RAID.

Indeed. The firmware hides pci devices behind this vmd thing. It is absolutely unstable and unfixable.

We have been using software raid1 for years on Intel hardware for industrial focused computers. However since Intel switched to VMD we started to get very odd problems like blue screens (windows) and spontaneous reboots and hard lockups where the raid volume wouldn't come back unless we did full power cycle. After some months we found a reproducer which we sent to our vendor, who in turn were able to reproduce it on different motherboards of different manufacturers with different chipsets supporting VMD. Until today we have not found a fix.

That is odd. Try another bootable linux distro like Fedora that has newer kernels and tools?

❯ nvme list
Node                  Generic               SN                   Model                                    Namespace  Usage                      Format           FW Rev
--------------------- --------------------- -------------------- ---------------------------------------- ---------- -------------------------- ---------------- --------
/dev/nvme0n1          /dev/ng0n1            123456789012         WD_BLACK SN850X HS 2000GB                0x1          2.00  TB /   2.00  TB      4 KiB +  0 B   620331WD

I'd guess that most SD Samsung SSD's are 512e unless the user changes it specifically. But the fact that it is not listed when you boot a live USB is a problem. Not sure why that would be. Perhaps some other BIOS setting is available? On my servers I can opt to use UEFI firmware from the NVME device or use the generic build-in firmware.

EDIT: Are you using too many PCIe devices? If not enough lanes are available it could be that the nvme device is not found. Another issue can be with PCIe-nvme adapters that required bifurbication..

@Kennet You need to boot in UEFI mode. And secondly, you must make sure your nvme is using 512e insted of 4kn sector size. You can use nvme-cli command to check sector size.

@jangar don't they have a statically linked version of storcli that can be downloaded?

Would sr-iov with xoa help backup speeds?

Hi,

It is not clear to me if the old XCP-ng PV drivers (8.2.2.200-RC1) are affected or not. How should we proceed if they are? AFAIK it is no easy task to migrate to WindowsUpdate drivers and it usually ends up with some issue.

@gudge25, Something like this