Can I restore VM/LXC backups created with Proxmox 8 in Proxmox 7?

[alpha754293]

My main server runs Proxmox 7 because it has a LSI/Avago/Broadcom MegaRAID 12 Gbps SAS 9361-8i HW RAID HBA in it and in one of my test systems, I tried installing Proxmox 8 directly on it, and it doesn't see the disks that's are attached to said HW RAID HBA (JBOD nor LVs).

So I am using Proxmox 7 instead.

However, on my other systems that doesn't have this HW RAID HBA, I have created VMs and LXCs.

Can I restore the backups from PBS for a VM/LXC that's created in Proxmox 8 on a system that's running Proxmox 7?

I don't use any of the newer features from Proxmox 8 (like SDN, etc.).

Should I expect or anticipate any issues with me trying/attempting to do something like this?

Also, for a system that is already running Proxmox 8, can I "downgrade" back to Proxmox 7? I know that there is the pve7to8 tool to help when you're upgrading, but what about downgrading?

Is there a "safe" way to do that or will that necessitate a full, clean, re-install of Proxmox 7?

Your help is greatly appreciated.

Thank you.

 

[alexskysilk]

Can I restore the backups from PBS for a VM/LXC that's created in Proxmox 8 on a system that's running Proxmox 7?

yes. bear in mind if the container type is not supported on the older environment it wont boot.

Also, for a system that is already running Proxmox 8, can I "downgrade" back to Proxmox 7? I know that there is the pve7to8 tool to help when you're upgrading, but what about downgrading?

No. its a full reinstall.

the question you should be asking is "SHOULD I run pve7 in 2025?" the answer is no, whether you use all the features or not. its not being patched. and pve8's days are numbered too- if you are starting from scratch you probably want pve9.

 

[alpha754293]

yes. bear in mind if the container type is not supported on the older environment it wont boot.

Would you have an example of a container type from Proxmox 8 that won't boot in Proxmox 7? I can't think of any off the top of my head.

the question you should be asking is "SHOULD I run pve7 in 2025?" the answer is no

As I stated in my OP, I tried to run Proxmox 8 but it doesn't work with the LSI/Avago/Broadcom MegaRAID 12 Gbps SAS HW RAID HBAs (like the 9361-8i, nor the 9341-8i) as noted here, here, here, and here.

If Proxmox 8 worked with these LSI MegaRAID 12 Gbps SAS HW RAID HBAs, then I would 100% agree with you.

But it doesn't, and therefore; I can't.

(And in reading through the other forum posts from here, linked above, there doesn't appear to be a firm commitment to get this fixed for Proxmox 8 neither, especially with the ISO installer, such that, ironically, I can "see" either my JBODs and/or LVs with the installer, but once the installer completes the installation, it no longer sees said JBODs nor LVs, which is incredibly frustrating. Like I don't understand why the installer would see it, but post-install, it won't. That's completely mind boggling to me.)

And the even weirder thing is that it works with Proxmox 7, so there were no expectations that it would be broken, out of the box, post-install, with Proxmox 8.

If I could (not run pve7), I would('ve). (I started with a pve8 install first, found this issue with the LSI MegaRAID SAS controllers, and then had to revert back to pve7, just to get my test system going.

if you are starting from scratch you probably want pve9.

Given how badly pve8 failed with the LSI MegaRAID SAS HW RAID HBA, I'm super hesistant to move up to pve9. pve7 seems to work with said MegaRAID SAS HW RAID HBA, so since it works, I'm not going to break it by updating/upgrading it.

 

[alexskysilk]

f Proxmox 8 worked with these LSI MegaRAID 12 Gbps SAS HW RAID HBAs, then I would 100% agree with you.

it does. the problems you are referencing had to do with issues specific to kernel version 6.8. simply install using an old (8.1) installer that used kernel version 6.5. or better yet pve9 and not bother with pve8 at all since it will be eol'd next year anyway.

 

[alpha754293]

simply install using an old (8.1) installer that used kernel version 6.5

I did try that.

It still didn't work.

better yet pve9 and not bother with pve8 at all since it will be eol'd next year anyway.

Given my MegaRAID SAS HW RAID HBA worked in 7, then failed to work with 8 (even with the pve8.1 installer), it's a coin toss right now as to whether it would work with pve9.

On the flip side, I know that said MegaRAID SAS HW RAID HBA works with pve7, so there's a mantra of stick with what works/if it ain't broke, don't break it.