I have a spare chromebook with unfortunately a emmc drive of 128GB.
The wear level is after 5 years of usage exceptionally well: 10-20% only.
I wanna run a full UEFI boot firmware with OpenSUSE Leap.
First I dual booted in legacy bios mode.
Loading the kernel takes minutes, however after booting the response is good.
Because of the slow emmc drive, is it ok to have the rootfs in btrfs? Or is it preferred to use ext4?
If btrfs is ok, do I need to do some extra config to minimize wear?
I can’t think of any reason why btrfs would cause more or less wear than ext4. With only 128 GB, ext4 looks better.
My guess is that people like btrfs because of the ability to take “snapshots”. If you take frequent snapshots, you will need more space overall. If you don’t use the snapshot feature, I don’t know why you would want to use btrfs over ext4 for a single disk.
I also suspect that ext4 will provide better performance, but I have never bench-marked an emmc drive, so it’s just an educated guess.
I use and recommend BTRFS’ compression feature. For my use case at least it reduces drive usage by 50%. Also due to how solid state drives rewrite larger chunks, a write tends to result in a larger actual write amount, which is called write amplification. Having more free space on the drive reduces write amplification. So with compression, you basically win twice in terms of minimizing wear. I’ve also used BTRFS+compression on small USB flash drives without problem. There’s a small cost due to metadata but overall it works nicely.
BTRFS supports different compression methods. Zstd appears to be the best overall option. For zstd, btrfs also supports different levels, 3 being the default if not specified and that’s what I’m using. The Fedora wiki details some tests contributors did with a fresh install which show that level 1, the fastest, is very close in compression ratio to 3, so they recommend level 1.
The only downside that I encountered is that enabling compression on an existing install is a bit involved because you essentially have to delete (or move) your snapshots first. Snapshots created after compression is used are unaffected and work beautifully as you’d expect on BTRFS.