[PSA] Swapping your Deck's filesystem to Btrfs is easy to do, and can give you more space for free

Submitted ⁨⁨1⁩ ⁨year⁩ ago⁩ by ⁨Fubarberry@sopuli.xyz⁩ to ⁨steamdeck@sopuli.xyz⁩

https://gitlab.com/popsulfr/steamos-btrfs

Btrfs is a filesystem (like FAT, NTFS, and ext4), but has some distinct advantages:

Increased storage - thanks to compression and file deduplication, Btrfs can save you considerable amounts of storage. I have 517G of files on my Deck’s SSD, but it only uses up 410G of storage to hold those files. Compressing your filesystem can also shorten load times, especially for slower memory devices like the SD card.
Snapshotting - save snapshots of the file system and easily roll back if there’s a problem.

Converting to Btrfs is easy to do, and doesn’t require having you to resetup/reconfigure your deck. The linked gitlab project will do the conversion, keep all your existing files and settings, and set all the Btrfs configurations for you. The file conversion will persist through updates, and it will setup automatic deduplication of files on the drive. It also allows the Deck to automatically mount Btrfs converted SD cards, and to format new cards in the same format.

Only potential downside I know of is that Btrfs is case sensitive, where the default ext4 on the Deck uses casefolding. Basically this means that Btrfs will treat File.txt and file.txt as two different files. I’ve never run into any issues with this, but I’ve heard it can cause issues with some specific mods that inconsistently capitalize their files.

Overall I’ve been using Btrfs for over 6+ months on my deck, and it’s been great. I highly recommend it. I’m not an expert on it, but I’ll do my best to answer any questions on it.

source

Comments

Sort:hotnew top

scrubbles@poptalk.scrubbles.tech ⁨1⁩ ⁨year⁩ ago
As someone who fell for the “Swap over to Fat32 and you’ll gain so much space” back in the day, I feel like I need to point out to newbies here, anything done to your file system has quite a bit of risk. Things can go wrong in a way that are unrecoverable unless you full reset your device. I’m not saying this project is unstable, but there is a high amount of risk involved with this.

If you decide to do this, back up all data that you may need saved and then mentally prepare that you may ultimately end up resetting your device in the end. These are real possibilities when messing with file systems.

source
- anlumo@feddit.de ⁨1⁩ ⁨year⁩ ago
  The real risk is losing a bit of time with this. Since everything is backed up anyways, the data is just a restore away.
  
  If you don’t have a backup, that’s the risk and has nothing to do with this procedure.
  
  source
skullgiver@popplesburger.hilciferous.nl ⁨1⁩ ⁨year⁩ ago
It should perhaps be noted that whole btrfs is pretty stable overall, I’ve run into two cases where deduplication corrupted the file system. I couldn’t get the files repaired either, they were just screwed up.

This could’ve been because of a simply bit flip, and the files were just temp files anyway, but it’s probably good to know about the risk before turning it on.

For something like a games console where you can just download the games again it’s probably fine regardless, but if you care you could use this knowledge to only use such features on SD cards to make sure the system is still bootable.

source
- anlumo@feddit.de ⁨1⁩ ⁨year⁩ ago
  Yeah, Linus Torvalds has been pushing for ECC RAM everywhere for just this reason.
  
  source
- yote_zip@pawb.social ⁨1⁩ ⁨year⁩ ago
  The filesystem metadata comes with 2 copies that can heal each other, and Copy-on-Write protects against power loss. The filesystem itself should be bulletproof.
  
  I feel like people reporting data loss on BTRFS are unaware that at least BTRFS is actually measuring the data loss. Bitrot is not rare, especially with how big our drives are getting. If you care about your data it should be backed up and/or RAIDed. Ext4 has no idea if your data is still intact - that’s not the same as no data loss.
  
  source
  - skullgiver@popplesburger.hilciferous.nl ⁨1⁩ ⁨year⁩ ago
    It should be, but neither files were damaged before the dedup attempt. I went balance-check-dedup-check-balance on purpose to make sure I wouldn’t accidentally deduplicate with a damaged extent. I don’t know if the metadata was damaged or the extent itself, but there were checksum failures on two specific extents in two sets of files that got deduplicated (4 files in total, both sets of temporary files in the Lutris cache).
    
    I’m not mad or anything, and I accept a few kilobytes of lost data every now and then. There’s a reason I have (signed, encrypted, diffed) backups in the first place! That doesn’t change the fact that there still are a few edge cases where BTRFS suffers corruption under heavy load with a wide range of features in use (many of which don’t even exist in other file systems, I myself am quite fond of CoW+deduplication of existing files+compression on selected paths+snapshots every time I run apt upgrade). If we all pretend these edge cases never happen, they’ll never get fixed.
    
    If this happened enough for me to be able to replicate the problem, I would’ve filed a bug report. I’m happily using btrfs on my desktop drives drives and I’m planning on converting my laptop as soon as I can get enough space for a full backup just in case. There’s no doubt BTRFS is superior to ext4, and even ZFS has issues BTRFS doesn’t have (no dumb Oracle licensing issues, for one).
    
    For something like a Steam Deck SD card, BTRFS is a no-brainer. I’m a little annoyed that I need to mount the SD card manually if it’s not ext4, but the space savings and improved loading times are worth it.
    
    source
    -> View More Comments
yote_zip@pawb.social ⁨1⁩ ⁨year⁩ ago
I noticed this guide recommends compress-force=zstd, which sets the ZSTD compression to level 3. There’s a BTRFS benchmark and ZFS benchmark of the ZSTD levels which can give a rough idea of how ZSTD performs for transparent filesystem compression. Note that almost all of ZSTD’s compression gains happen starting at level 1, and levels after that have very minor improvements.

Also keep in mind that ZSTD levels only affect how long it takes to write new data to the filesystem. ZSTD is somewhat unique as a compression algorithm in that as you increase compression effort, the decompression effort stays the same. You could compress everything with level 23 and it will decompress just as fast as level 1 (~generally). Setting higher ZSTD levels could arguably make more sense for a gaming drive because the data is usually write-once, read-many. I don’t know at what level the Steam Deck CPU will limiting your I/O though.

BTRFS compression is enabled per-file, so you can change ZSTD levels at any time and old data will still be compressed with your previous algorithm. To recompress using a new level, change your /etc/fstab/ ZSTD level and remount the partition, then run a defrag to poke the data into recompression.

source
twistypencil@lemmy.world ⁨1⁩ ⁨year⁩ ago
I’ve tried btrfs twice, and both times I regretted it. I also regret XFS, and reiserfs, but I had to do that because ext2 could just not deal with the very large, deep and multitudinous number of files I had to manage. Oh and jfs, also regret.

source
- Nagairius@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
  Really? I have run BTRFS for that last 3 years on my desktop and my laptop and it has saved me quite a few times now and I have yet to have any issues tied back to my filesystem.
  
  source
  - twistypencil@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Maybe I used it too early, dunno.
    
    source
    -> View More Comments
- anlumo@feddit.de ⁨1⁩ ⁨year⁩ ago
  You should try ZFS (not on the SD, though). It’s pretty solid and used in NAS very often.
  
  source
- vagrantprodigy@lemmy.whynotdrs.org ⁨1⁩ ⁨year⁩ ago
  I’ve had great luck with xfs and zfs, but btrfs has lost data for me more than once.
  
  source
kadu@lemmy.world ⁨1⁩ ⁨year⁩ ago

Compressing your filesystem can also shorten load times

At the cost of adding pressure to the already limited CPU.

source
Luci@lemmy.ca ⁨1⁩ ⁨year⁩ ago
To get around the case folding issue you could mount your steamapps/common folder as a loop device with ext4 with case folding support. The virtual device should follow the compression settings without too much issue but deduplication won’t be an option and snapshots may be larger.

source
lbj@lemmy.world ⁨1⁩ ⁨year⁩ ago
I’m a big fan of BTRFS, I use it in my desktop and laptop but I’d be curious if the compression is worth the battery & compute trade off. I’m not sure how much battery/compute is used day to day to decompress and compress files read and written. But I guess it depends on which is more valuable, battery or storage.

source