Which folders and files do I need to exclude from TimeShift?
Also is there a way to also exclude programs installed as .deb ?
I doing this to reduce Backup size as I have limited storage.
100GB - Windows 11
400GB - Storage
400GB - Mint
100GB - TimeShift
Then you will need to also include most if not all system packages. You can exclude your home folder if you want.
Note that there are big differences between how Timeshift works on btrfs or on anything else. BTRFS snapshots allow something called “copy on write”, basically allowing the system to make a “copy” of a file that references the same data as another, and from that moment only tracking changes. That way, you can instantly create snapshots of entire drives, and keep dozens of snapshots without risking running out of storage. I’ve got my system set up to make a snapshot every time software updates are installed and the biggest snapshot I’ve seen was about 45GB (it was a snapshot from before upgrading Ubuntu 22.04 to 24.04 and included a few virtual machine and ML models). My daily apt upgrades generate snapshots of about 100MB but I can still roll back the moment I need to. I can even select an older snapshot in my Grub boot menu in case my bootloader dies.
The rsync based approach used on ext4 and other filesystems isn’t that flexible. You’ll get snapshots, but each file needs to be processed individually. This means you need to make sure to close down programs before making snapshots or you’ll risk corruption. The disk space savings are also more limited; filesystems like ext4 will still have almost 0 overhead for files that haven’t been changed between two snapshots, but if you change a single bit in the middle of a 100MB file, chances are rsync will create a fresh copy (whereas btrfs would only store an extra extent, usually 4KB, which is the smallest unit the filesystem will let you control).
Restoring snapshots using rsync requires copying/linking files back, and can’t be done transparently. This means you can’t boot a previous version of the system like on btrfs, you’ll need to boot into recovery mode, restore the snapshot manually, and reboot.
Support is mature enough that it’ll Just Work in most cases. With some edge cases, like disk usage statistics not being accurate, because tools don’t realise files can be partially deduplicated or compressed, let alone taking subvolume quotas into account. In most cases, the more fancy features you enable, the more older software will act a bit funny.
I believe Fedora has picked it as the default for a few years now. Haven’t checked, though.
Tools like
dfand other file system monitors only support very rudimentary disk usage statistics, even when certain ext4 features are involved. There are a bunch of methods in which btrfs can seem full, but still have plenty of space, or it can seem like there are gigabytes of space left but the volume is so unbalanced that that space isn’t actually usable. There are also about three types of data stores that can technically get full (though your rarely run into that). Usually, you can claim back a chunk of storage after a year or two by rebalancing and defragmenting the file system, especially if you use advanced features like snapshotting. I believe there are rolls to automatically run these operations as well.These issues seem to come up. Most when you’ve nearly filled the FS to the brim. Keeping 10% free seems to prevent most of them from ever popping up.
There are a few other edge cases as well (like how you should disable compression on swap files and virtual machine images, and how you may want to disable copy on write and snapshots on them as well for performance reasons) but they’re more niche. There are a bunch of really cool features as well (like how you can send a snapshot over the network in the form of only the difference since the version before, making network disk backups tiny). You’re not that likely to run into any of them, but the project website has everything documented if you’re interested.
Thanks man. you rock.
I learned a lot. Now, I’m planning to use BTRFS in a VM first to understand it fully.
What’s
dfthough?😅 Is it like cli file manager.The problems you mentioned regarding the remaining space left on BTRFS, they occur on GUI file managers too?
df is the standard command line tool to see how much of your disk space is free.
The problems happen in GUI tools too. Most of the time, they work out in your favour (you think you only have 10GB left but you can put 15GB away) but after a lot of deletes you may “lose” some space until you do a rebalance even through you’d think looking at the stats that you have plenty of space.
Another issue is that file managers showing you a file’s size often don’t know about compression. You can store a large text file with standard compression on a disk and have it be reported as 100MB while it only takes up a megabyte of space. You can end up deleting a whole bunch of “hundred megabyte files” and save basically no disk space. Other file types, like images and video, often do represent the real size as they’re already compressed, making some 100MB files larger than others. If you don’t enable compression, you won’t have this problem, or course.
GUI tools also often don’t know about CoW. If you copy a file on BTRFS, the copy action should be instant and take up maybe a couple hundred bytes for the new metadata. To your file manager it looks like you have two 3GB movie files, but in practice they’re just names pointing to the same directory. You can get petabytes of used disk space this way by just making more and more copies, even though your actual disk space barely grows. This also means deleting files may not clear up as much disk space as you’d like.
🥲
How do you manage this though?
I take advantage of the free disk space savings and don’t worry about disk space much. I’ll clear out my download directory and maybe some caches when my disk usage grows beyond 80% (as reported in GUI tools). Running
duperemoveacross my drive every now and then also tends to help a lot without deleting anything.If I do run out of space, there are a few interactive terminal tools that’ll point out the biggest files so I can delete them and save some space in a pinch. I practice, I just don’t really think about it much.