XFS Disk Usage
Posted by Burine@reddit | linuxadmin | View on Reddit | 7 comments
In process of building a DYI NAS. I prefer RPM distros and run Fedora KDE on my PC, but I wanted something more "stable" for the NAS so I went with Alma KDE. I put a few HDDs in and formatted using XFS.
[XXX@NAS DATA]$ df -Th
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs tmpfs 7.7G 0 7.7G 0% /dev/shm
tmpfs tmpfs 3.1G 24M 3.1G 1% /run
/dev/mapper/almalinux_localhost--live-root xfs 70G 14G 57G 20% /
tmpfs tmpfs 7.7G 4.0K 7.7G 1% /tmp
/dev/mapper/almalinux_localhost--live-home xfs 159G 2.2G 157G 2% /home
/dev/nvme0n1p2 xfs 960M 595M 366M 62% /boot
/dev/sda1 xfs 3.7T 26G 3.7T 1% /DATA
/dev/sdb1 xfs 233G 42G 192G 18% /MISC
/dev/nvme0n1p1 vfat 599M 9.5M 590M 2% /boot/efi
tmpfs tmpfs 1.6G 124K 1.6G 1% /run/user/1000
SDA is a 4 TB drive and SDB is a 256 GB drive. Usage of SDA1 is 26 GB, according to this command, but I have no file on it.
[XXX@NAS DATA]$ sudo du -h
4.0K ./.Trash-1000/info
0 ./.Trash-1000/files
4.0K ./.Trash-1000
4.0K ./New Folder
12K .
I have a "test" folder and a "test" file in that folder, totaling only a few K. So why does df show 26 GB used? Is it the journal? Is it the metadata?
SDB1 contains my various .iso file that I've been distro-hopping with and shows 40 GB used of the above reported 42 GB used, so only 2 GB discrepancy vs >25 GB discrepancy on my 4 TB drive.
[XXX@NAS MISC]$ du -h
40G ./ISO
40G .
reingauf@reddit
filesystem overhead - crc, finobt, reflink, and such features, unfortunately cause a lot of metadata reserved
you can disable then at mkfs time but youd get a xfs filesystem that does not have the bells and whistles
depends how you intend to use it
Burine@reddit (OP)
I'm eventually going to buy some more HDDs and configure RAID for household file storage and PC backups. Alma defaults to XFS it looks like, and RHEL and clones don't natively support BTRFS like Fedora does, so I figured I'd stick to something native.
reingauf@reddit
I've been using XFS for over a decade, it has never failed me. And I had a faulty power strip at some point that caused the system to reset and it took me 2 weeks to identify the cause. Filesystem survived regardless.
I still use ext4 and other filesystem for backups just for the sake of not putting everything in to one basket. All data is just one kernel bug away from getting zerofied.
DougEubanks@reddit
Usually on some file systems, by default you have 5% of the disk reserved for the super user so a regular use can’t drive the disk to 100% and crash the server.
It’s been ages since I ran XFS and I can’t recall if XFS falls into that category.
If so, it’s usually tunable using the filesystem specific tuning tools.
aioeu@reddit
It does not.
Superuser-reserved disk space seems to be a uniquely Ext2/3/4 thing. I haven't seen it in any other filesystem.
bush_nugget@reddit
Yes.
26/3,700 and 2/233 (dropping the 40G of ISOs from the math) both equal less than 1% of available space being used (0.007 & 0.008, respectively).
There's no discrepancy, just a ratio.
Burine@reddit (OP)
Ah, that makes sense.