Booting to Dracut (I trusted ChatGPT)
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@nuentes i GUESS if you make a clean reinstall
then restore the metadata... you should be up & running againBEWARE before reinstalling, be sure you can restore said metadatas ! I don't want you to be in any more troubles
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@nuentes No. My intention was to rise awareness of USB (un)reliability, especially the reliability of USB attached storage. Also, either I'm blind or there is no mention of your system not being installed on USB storage.
You said everything yourself. Your problems started with USB which you assumed can be fixed by flicking some kernel parameters. In the process of "fixing", you destroyed your system. Unfortunately, I believe that the system is now beyond repair via interactive forum session because no one knows what really happened. Backup is your best friend.
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@bvitnik You're right. I added a lot of details, but neglected to mention that I'm not booting from USB.
I'm really not convinced I've destroyed my system. I truly think that's an over-reaction. I think I ruined my initrd and initramfs files, yes. But that should be recoverable. I haven't done nearly as much as you think I have. The reason I haven't succeeded in that yet is because I'm not really convinced I've been doing it the right way.
Since my my disks run in RAID, my system has like 6 partitions.
md127p1
md127p2
md127p3
md127p4
md127p5
md127p6From memory, p1 and p2 are very similar. However p1 doesn't include grub (/boot/efi/EFI). P4 is grub. P2 looks very similar to p1, but it includes grub. P3 is my VHDs. P5 is maybe swap, and I can't remember what the other one is.
My point is that I don't believe that I've mounted everything correctly through the shell in order to be able to successfully chroot into the device and be able to run the dracut commands successfully. When I run the dracut commands, I see failures for applications that I can see in the sbin folder.
So there is something that I'm missing in mounting these disks in the shell that is preventing me from solving this issue. This is why I'm here. I'm not here for lectures about the dangers of USB.
Alternatively, I could boot the install media and simply perform a metadata/pool restore from backup, but I just want someone to tell me that's an actual viable option.
I'm not going to simply re-install the OS. If I do, I'll clone it first, and then boot the clone and test a metadata restore. But that's a lot of work for it to fail.
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@nuentes Oh no, no. Your system is not destroyed beyond repair. It can be repaired. It's just that it is almost impossible or too much of a hustle for anyone to try to help you over forum. Someone has to sit in front of your machine to do it.
My only guess is that ChatGPT instructed you to make changes based on a CentOS system but XCP-ng and Xen virtualization in general is much different than regular CentOS. It has two stage boot process. First the Xen kernel boots and then a special virtual machine called Dom0 is booted. What you are accessing and reconfiguring is in fact this VM, not the underlying "system". So it's like a two layer system and some configuration must be done on Xen layer, some on Dom0 layer. I'm unfortunately unfamiliar with exact specifics on kernel and initrd image generation for this case so I can't spot where thing have gone wrong.
In short terms. Instead of going back and forth and trying a lot of different things, it's more time saving and simpler to reinstall the system and restore metadata if you already have a backup.
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Let's say you don't have the metadata backed up... Is there a way to boot from a rescue disk and save the metadata?
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@Greg_E Theoretically yes. I've never been in such situation so I would have to learn, experiment and improvise along the way. If you can mount the file system of the host, you can find XAPI database in this location:
/var/lib/xcp/state.dbThis is an XML formated file. I don't know if this is the same format as metadata backup (I think it's JSON instead). So you could possibly restore this file to proper location and restart the host but you would probably need to change some references in it, like UUIDs of local file systems on a freshly installed system. Other possibility is that the state file could be converted to metadata backup and imported but I'm not aware of there being any such conversion tool. It would have to be improvised.
There is always alot you can do. It just depends how deep you want to go, how complex you can go and how much time you can spare.
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@bvitnik I'm still unclear what metadata backs up. I suppose I don't need to know specifically, but I'm assuming it doesn't include initramfs and initrd? So a simple metadata restore would not resolve my issue, presumably?
I'm worried about doing a reinstall - I'm assuming that would wipe the disk (although I know sometimes that's not the case with Linux reinstalls). I would prefer to preserve my VMs if possible. If I'm expecting to need to wipe the disk, then I'm not 100% certain that I have backups of all of my VMs, so I'd like to clone the disk. I ran into some issues trying to run clonezilla the other night, so I might just pull the SSD and clone it to another SSD bit for bit with a disk cloning enclosure.
Just to point out - yes, my system has been offline for approaching a week now. But I've recently moved, so I have a lot of other things going on in life right now. I'd like to get it back online asap of course, but life keeps getting in the way. I feel that you are over-estimating how much I've done and mucked about. Anything I've actually performed is pretty full documented in this thread
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@nuentes I explored my pool metadata backups, and I see a "part.1" file, that is a big XML of all the configuration of the pool
so yeah I don't think there is something else in here like your OS parameters, only pool config.
I could be wrong, but it's all I can see in here
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@nuentes You can reinstall without wiping the SR. Just plug the ISO, it will ask you if you want a clean install or a reinstall
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@AtaxyaNetwork yeah but if he doesn't have metadata backups, he will have SRs full of disconnected VDIs ? and the need to recreate each VM ?
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If I was in your place, I would do:
- Disconnect all USB used as SR
- Reinstall XCP-ng
- if you have only a few VMs, my option would be just to redeploy XOA, REATTACH the SR (not create, REATTACH, be careful, a create will wipe your disk)
- Recreate VMs, attach the VDI, boot from here
- if you have to many VM, directly after deploying XOA restore your metadata backup, it should be repluging the SR and create PDB at least (but it's been a while since I didn't use the metadata)
In any case, backup everything, especially the VDI (.vhd). If you have the VDI, you can work around with the rest
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@nuentes metadata in this context is just XAPI database. In other words, it only contains information about your VMs, SRs, networks, pools etc. It does not contain anything system level. It is not a backup of the host system.
As far as I know, but someone from Vates can confirm, metadata backup functionality in XO is based on XAPI
pool-dump-databasecommand:xe pool-dump-database file-name=dump.xmlThere is some info about it here:
https://docs.xenserver.com/en-us/xenserver/8/dr/backup.html
P.S. I guess metadata backup is also XML just like XAPI state file (database). I don't know why JSON came to my mind regarding metadata backup.
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@bvitnik said in Booting to Dracut (I trusted ChatGPT):
P.S. I guess metadata backup is also XML just like XAPI state file (database). I don't know why JSON came to my mind regarding metadata backup.
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perhaps because of other thread discussing metadatabackup.list in audit log
there is actually a bug there where the metadata is not only checked to be audited, but also completly dumped in JSON format.
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(BTW you don't have any backup from XOA ? If you have backup, you can just register a new XOA, connect to you remote and restore everything, it will be much simpler)
