Fusion 12/13 Ubuntu 16.04 corrupted ????

[philippeannet]

just looking for someone who maybe came across similar issue(s).

My 2019 MBP had a h/w issue, and had its mainboard changed (thus ssd inclusive).

I was using the last 12.x Fusion Pro, with macOS Monterey 12.6.1. The repaired Mac came back with Ventura installed. After restoring the latest Time Machine backup, I had many compatibility issues reported by macOS, and I decided to upgrade to Fusion 13, something I'd have done soon anyway.

Then, when I booted my Windows (10, 7, XP) VM's, it just asked whether they were copied or moved, and whether or not to upgrade these. They all started flawlessly.

My Ubuntu 16.04 instead didn't boot, booting only showed the Grub menu, but no disk. I Looked in the logs but found nothing to chew, then I started the VM from CD (Ubuntu 22.04), and mounted the disk (/dev/sda1). I reported quite a bunch of errors, so I ran fsck, but afterwards many files (in particular, those I really needed...) contained just garbage...

The very strange thing, is that I know I've used that VM successfully many, many times in the last past months, and now, regardless what backup I take from Time Machine (got about 10 months of history), 1) it doesn't boot, and 2) if I start from a live Ubuntu, the same files are always corrupted...

Something looks basically wrong here (why the heck can't I start any of the previous versions of that VM), but I really can't figure out what... any idea/suggestion welcome.

[Technogeezer]

Were those backups of your VMs taken with Time Machine? Time Machine is not recommended by VMware for VM backups - many instances of corrupt VM backups have been reported.

[philippeannet]

Yes... TM used to backup the whole Mac. And all my VM's are stored locally. It's not the first time I restore my Mac (or change Mac), never had trouble.

My impression is indeed that some 'root' file has somehow became corrupt on TM, and that would explain why, whatever version I restore, I get the same file-system issues (which I did NOT have at the date the backup is from)...

If the TM backup was fine, I should be able to restore a working version of that VM, by getting back to some date in the past 10 months, but that doesn't work for me. Strange though that just that one VM is affected...??

[Technogeezer]

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@philippeannetwrote:

Yes... TM used to backup the whole Mac. And all my VM's are stored locally. It's not the first time I restore my Mac (or change Mac), never had trouble.

My impression is indeed that some 'root' file has somehow became corrupt on TM, and that would explain why, whatever version I restore, I get the same file-system issues (which I did NOT have at the date the backup is from)...

If the TM backup was fine, I should be able to restore a working version of that VM, by getting back to some date in the past 10 months, but that doesn't work for me. Strange though that just that one VM is affected...??

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Thought: Was that VM backed up while it was running? Backups of running VMs are even more problematic as there's no coordination between VM activity and the backup activity.

[philippeannet]

well... you don't control that once TM is in auto mode... yes, some backups are taken while VM's are running obviously, and some not...

But it's definitely a good lesson: DO NOT COUNT on TimeMachine for taking VM backups !

I'm still not 100% sure, as I tried many 'variations', from the very first version I had (January 2022, til November 2022), and none of these worked correctly. The most 'plausible' explanation being that some file(s) of the earliest backup I have of that VM was or became corrupt, and I did not restore anything since January this year, so I didn't notice that.

I'm likely to be able to reconstruct the missing or corrupt files to some extent, but gee, what a useless way to spend one's time...

[Technogeezer]

Yes, rebuilding the contents of a VM is boatloads of fun. I wish I could come up with a better answer for you - perhaps others might have another idea. But there have been lots of folks posting here that have gotten burned by Time Machine backups and didn't find out the backups were suspect until they needed them.

I always exclude VMs from Time Machine backups for this very reason. And also because backups of VMs using Time Machine are very inefficient in the use of backup storage. I've gotten into the habit of periodically copying those VMs to external storage while they're shut down.

There's also a utility specifically for backing up Fusion and Workstation VMs - Vimalin (https://www.vimalin.com) - that I've used very successfully. It can be used for free to back up VMs manually, with a paid mode that can take backups of VMs automatically. It has the ability to do some behind the scenes magic to back up a VM even if it's running.

On a side note (and not that I'm recommending Time Machine for VM backups) Ventura now has a bit more selectivity in its Time Machine backup scheduling. It'll allow you to run Time Machine automatic backups hourly, daily, weekly or no automatic backups at all.

[ColoradoMarmot]

Part of the issue with time machine is that it can age out different files at different times, so inside the virtual machine, one part of the virtual disk could be from a different time slice than others.

TM is also a problem when you run VM's disconnected - it maintains local snapshots of the changed files until the actual TM volume comes back online - I've had those consume all my available disk space on the internal drive during an extended trip. The new architecture is somewhat brittle, and I'm really considering just dropping it and using carbon copy cloner daily clones as my sole backup mechanism.

[Technogeezer]

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@ColoradoMarmotwrote:

Part of the issue with time machine is that it can age out different files at different times, so inside the virtual machine, one part of the virtual disk could be from a different time slice than others.

That's not as much of an issue for Time Machine backups of APFS formatted disks taken to APFS formatted backup disks. The source disk is snapshotted before backup and the files backed up from there. The destination backup disk is snapshotted after a backup is taken. No files are removed from active snapshots if a backup disk snapshot is aged out. It still doesn't solve the problem of Time Machine taking a backup of a running VM.

TM is also a problem when you run VM's disconnected - it maintains local snapshots of the changed files until the actual TM volume comes back online - I've had those consume all my available disk space on the internal drive during an extended trip. The new architecture is somewhat brittle, and I'm really considering just dropping it and using carbon copy cloner daily clones as my sole backup mechanism.

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If your boot drive is an SSD and you wish to store your VMs on it, you might want to consider creating a new APFS volume on the boot disk, put your VMs in there, and then exclude that APFS volume from Time Machine. That'll keep Time Machine from wasting space by snapshotting actively running VMs that you arent going to back up with Time Machine anyway.

[philippeannet]

The situation is not black/white... from all my VM's (9), only one had trouble (corrupted file system inside the VM) after I had restored my Mac (2TB SSD, 1.3 used).

So while I'll definitely put some additional measures in place to snapshot complete VM's from time to time, TM's ability to revert to some precise moment can be quite handy... I'm running TimeMachine on Synology with an 8TB disk (which is used only for my Mac), so I can certainly grab a few hundreds GB to snapshot the VM's from time to time on top of the TM backup.