File system

A file system controls how an operating system stores and retrieves data on a storage device. It defines the structure for files and directories, handles metadata (permissions, timestamps, ownership), and enforces access controls including disk quotas.

File systems on PM seedboxes

Pulsed Media servers run ext4 as the primary file system. All RAID arrays, including the /home partition where user data lives, use ext4.

Ext4 was chosen because it is the Linux standard, well-tested under long-term production loads, and supports Linux disk quotas natively. Quota enforcement for seedbox accounts runs directly on ext4.

Proxmox hosts (the physical machines running VM clusters) use ext4 or ZFS for VM image storage, depending on the host configuration.

Comparison

File system	Use at PM	Journal	Quota support	Notes
ext4	All RAID arrays, `/home`	Yes (ordered mode)	Linux disk quotas	Default on all seedbox servers
XFS	Some specific use cases	Yes (write-ahead)	Project quotas	Better throughput on very large files; weaker with many small files
Btrfs	Not used on seedbox arrays	Copy-on-write	Subvolume quotas	Snapshot support; higher overhead under sustained writes
ZFS	Proxmox VM storage (some hosts)	Copy-on-write (ZIL)	Dataset quotas	Strong data integrity; requires more RAM

Seedbox performance considerations

Seedboxes produce a specific workload: many small files (torrent pieces, metadata), large sequential writes during downloads, and sustained read throughput during seeding.

Journaling overhead: Ext4's default ordered-mode journaling syncs metadata before data, protecting against corruption after unclean shutdowns. The overhead is low for sequential writes and not a practical bottleneck for seedbox activity.

Inode limits: Ext4 pre-allocates inodes at format time. A volume with hundreds of thousands of small files can run out of inodes before it runs out of space. If df -h shows space available but you cannot create files, check inodes with df -i.

Fragmentation: Heavy mixed-read/write workloads fragment files over time. Ext4 uses delayed allocation to reduce this. On modern hardware with fast storage, fragmentation is rarely severe enough to notice.

Checking disk usage

Space

df -h /home

Shows mounted volumes with space used and available.

Inodes

df -i /home

A filesystem at 100% inode use cannot create new files regardless of free space.

Directory sizes

du -sh ~/torrents/

Shows actual disk usage for a specific path. The -s flag gives a single summary figure.

Quota

Seedbox accounts have a disk quota enforced at the file system level:

quota -u USERNAME

Full details on how quota works: Seedbox Storage Quota.