The Sneaky Problem of Full Storage: How Proxmox Users Are Beating LVM-Thin Bloat

Actually, in the self-hosted world, everything looks good—until it doesn't. And that's what tons of Proxmox users figure out the hard way when their LVM-Thin storage pools just... fill up. No big warning signs, no crazy red alerts, just a slow crash: backups stop working, virtual machines freeze up, and everything grinds to a stop. LVM-Thin is pretty awesome for making storage work better, letting users create thin volumes that only use space when you actually write data. But here's the thing—its best feature is also what kills it. By design, it lets you promise more storage than you have. Without keeping an eye on things, stuff goes bad real quick. Here's how this mess usually starts: Some self-hoster gets a 1TB NVMe, puts Proxmox on it, and sets it up as local-lvm—the basic LVM-Thin pool. Over time, they throw in more VMs, containers, maybe mess around with Docker, and boom—that drive hits 88% full and keeps climbing. Add some failed backups and now you're freaking out. So what are folks actually doing to fix this nightmare? Let's look at the real tricks the Proxmox community uses to fight LVM-Thin bloat. ## The Reality Check: When Full Actually Means Dead One Proxmox user painted the picture perfectly: their OPNsense VM would boot up, then just freeze for no reason. After two hours of trying to figure it out, they found the problem—LVM-Thin had maxed out at 100%. And get this: no alert, no heads up. Just silent death. This isn't some weird edge case. Unlike regular file systems that scream when space gets low, LVM-Thin just lets you keep going... until you can't anymore. This quiet failure is what makes it so nasty. "I made a cronjob to email me when disk usage hits 85%," one user said. "Can't believe Proxmox doesn't do that out of the box." ## Fix 1: Grow Your Storage Pool (Without Destroying Everything) When a disk fills up, your first thought is probably to upgrade—swap that NVMe for something bigger. But that's not always doable, especially if you don't want to blow everything up and start over. Instead, people are adding new SSDs and stretching the volume group. This keeps your VMs and containers running while giving you more room to breathe. The steps are simpler than they sound: 1. Install a new SSD 2. Set it up as a physical volume (pvcreate) 3. Add it to your current volume group (vgextend) 4. Done—your thin pool now uses multiple drives Sure, there's some risk. "If one disk dies, the whole volume group can break," someone mentioned. But with decent SSDs and solid backups, it's a risk most people can live with. ## Fix 2: Get the Backups Off That SSD Here's where lots of setups shoot themselves in the foot: running backups on the same disk as the VMs. It's asking for trouble. Users suggest cleaning out old backups and, more importantly, moving them somewhere else entirely. Got a NAS? Use it. Don't have one? Mount another drive and point your backups there. One experienced Proxmox user dropped this wisdom: "Use Proxmox Backup Server (PBS). It removes duplicates. I'm storing 350GB of data that would normally eat 5TB." PBS isn't just backup software—it's a smart storage saver. Deduplication, compression, and moving stuff off your main drive all rolled into one. Some people run it on a different machine, others on a VM inside Proxmox itself. Either way, it's huge for keeping your thin pool sane. ## Fix 3: Clean Out the Junk When space gets tight, every gigabyte matters. Docker users keep mentioning the same fix: prune everything. Old containers, unused volumes, hanging images—delete them all. "I got back over 100GB just by pruning Docker," one homelabber bragged. It's a good reminder that your disk isn't just filling up with VM stuff—it's also collecting leftover garbage from tools, builds, and experiments you probably forgot about. Set up regular Docker cleaning if you're running containers, and think about clearing out any old ISO files or logs hiding around. ## Fix 4: Turn On TRIM and Discard Here's another trick people miss: enable TRIM on your LVM-Thin volumes. When files get deleted inside a VM or container, the space doesn't automatically come back to the host. You have to manually discard it. "Turn on the 'Discard' option on the VM drives and make sure fstrim.timer is running inside the guest OS," a user suggested. This helps stop ghost usage—where the guest thinks it deleted data but the thin pool still counts it against your limit. It's not magic, but in systems that write and delete a lot, it adds up. ## Fix 5: Ditch LVM-Thin Completely? A few bold people have gone a totally different way: dropping LVM-Thin for file systems like BTRFS or ZFS. These give you built-in snapshots, compression, and better visibility into what's eating your space. "I switched to BTRFS to get better usage," one poster said. "Backed up my VMs to PBS, wiped the drive, and restored." It's a big move—but for some, the control and insight make it worth the hassle. That said, switching file systems is major work. If you're already deep into LVM-Thin, it might be smarter to optimize what you have instead of nuking your whole setup. ## Don't Wait for Disaster What's crazy about all this is how preventable it is—if you stay ahead of it. Set up disk alerts. Move your backups. Clean aggressively. Watch your usage like a hawk. A maxed-out LVM-Thin pool isn't just a storage headache—it's a stability bomb waiting to go off. When it hits 100%, VMs freeze, backups die, and recovery gets messy. But with some smart moves and community knowledge, you can dodge the worst of it. The real takeaway? In self-hosting, getting comfortable is dangerous. Your server won't yell when things start breaking. But if you pay attention—and take the right steps—you can keep your homelab running smooth without losing sleep over a storage time bomb. ## Quick Fixes From Real Users | Solution | What It Does | |----------|--------------| | Add new SSD + expand volume group | More space without rebuilding | | Move backups to separate drive/PBS | Stops backup bloat on main disk | | Prune Docker + clean cruft | Frees up forgotten storage | | Enable TRIM/discard | Gets space back from deleted files | | Set up disk alerts early | Warns you before disaster | | Consider file system switch | Fresh start with better tools | Storage problems rarely announce themselves loud and clear—they sneak up on you. But you don't have to let them win.