v !!! POST-MIGRATION EDIT !!! v
I shrunk the LVM partition by 5000 MiB and just ran dd overnight. I had to shuffle my boot-order around a bunch to find the one partition that would boot properly but it all just works.
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v !!! ORIGINAL POST !!! v
Hi! My Proxmox machine has 3 disks (see pic). I wish to migrate sdc to a 2TB SSD. I have LXCs on all drives and I would really like to avoid having to restart from backups. I don’t have any special configuration on my proxmox, it’s pretty clean and basic.
Is it safe to simply dd the old disk to the new one? I can’t find an explicit answer to this question that doesn’t also have a lot of other variables not relevant to me.
If not, what else can I do?
There’s nothing wrong with using DD for this, but unless you’re sure of the geometry of the new SSD, you may run into issues. The size of your new SSD needs to be exactly the same size or larger to fit the existing partitions of sdc since you’d be doing a block copy. Get a slightly larger drive to be safe and you’ll be fine.
Honestly, DD is hard mode for this. Use a cloner that checks these things or shrinks partitions beforehand to prevent issues if you decide to go with a 2TB SSD.
Couldn’t I just shrink a partition myself? I could clone the LXCs to the 4TB drive and just shrink the LVM partition significantly. DD the disks, recreate the LVM on the new SSD and move em back, right?
Using a larger disk isn’t an option, unfortunately. I don’t have that kind of money.
Yeah, you can do that as well. Just mentioning that DD isn’t the simplest way to achieve what you want.
It might not be, but I am intimately familiar with it. It’s proxmox itself that’s the wildcard here. I will shrink the LVM and then DD it to the new disk.
I’d prefer GNU’s ddrescue just because I find it more robust and has better progress output. It’s functionally the same interface but lets you use a mapfile to resume sessions should anything happen to interrupt the copy.
Arguably I’m against this because you never know what’s going to happen and the conventional wisdom for appliances like this is to just backup any important configs, backup your containers and vms, then do a fresh install from the latest install media on the new disk followed by a restore of the backups. It might take a little more time but it’s negligible and allows you an opportunity to review your current configs, make necessary changes, and ensure your backups are working as intended.
The issue is that I can’t really fit all of the data somewhere else. Can I shove it onto the 4TB drive and then mount it on a new proxmox install and recover from there?The answer was a resounding no
Proxmox is just Debian. Use any partition-aware copy tool. If you have it set up for UEFI, just copy the EFI partition and all that stuff too and you should be set.
I was in your position recently and decided to install PVE from scratch and restore VMs from backup.
I had a fairly complex PVE config so it took some additional work to get everything up and running. But it was absolutely worth it.
I think dd is the right tool for the job. Consider using pv though. It can be much much faster.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I’ve seen in this thread:
Fewer Letters More Letters LVM (Linux) Logical Volume Manager for filesystem mapping LXC Linux Containers SSD Solid State Drive mass storage
3 acronyms in this thread; the most compressed thread commented on today has 6 acronyms.
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