df

The df (Disk Filesystem) command is used to display information about the total, used, and available disk space on all mounted filesystems in a Linux environment. It helps system administrators and users monitor storage usage and identify disks that may be reaching capacity.

CODE

df -kh

Option	Description
-k	Displays filesystem information in 1024-byte (KB) blocks.
-h	Prints sizes in a human-readable format (e.g., KB, MB, GB, TB).

This combination (-kh) provides an easy-to-read summary of disk usage across all mounted partitions.

Example Output

CODE

Filesystem Size Used Avail Use% Mounted on 
devtmpfs 63G 0 63G 0% /dev 
tmpfs 63G 12K 63G 1% /dev/shm 
tmpfs 63G 178M 63G 1% /run 
/dev/mapper/xcatvg-root 57G 6.8G 50G 12% / 
/dev/sda2 1014M 204M 811M 21% /boot 
/dev/sda1 256M 5.8M 250M 3% /boot/efi 
beegfs_nodev 98T 66T 33T 68% /mnt/beegfs-home 
beegfs_nodev 294T 15T 279T 6% /mnt/beegfs-scratch 
ibapp:/drbd/pub 4.0T 402G 3.6T 10% /opt/ohpc/pub 
xcat-mgmt:/install 128G 33G 96G 26% /install 
ibnfsgw:/srv/kuttam_fg 198T 138T 61T 70% /kuttam_fg 
ibnfsgw:/srv/datasets 100T 87T 13T 88% /datasets 
ibnfsgw:/srv/userfiles 77T 73T 3.7T 96% /userfiles 
ibnfsgw:/srv/frozen 372T 128T 245T 35% /frozen 
ibtmpfs:/srv/tmp 1007G 0 956G 0% /singularity

Key Mount Points from Example Output

Mount Point	Filesystem Type / Source	Purpose / Description
/	Local disk (/dev/mapper/xcatvg-root)	Root filesystem; operating system and core binaries.
/boot, /boot/efi	Local partitions (/dev/sda1, /dev/sda2)	Boot and EFI partitions for the OS kernel and bootloader.
/mnt/beegfs-home	BeeGFS	Central user home directories for cluster users.
/mnt/beegfs-scratch	BeeGFS	High-performance scratch space for temporary job data. Not backed up.
/opt/ohpc/pub	NFS mount (ibapp:/drbd/pub)	Shared public applications and software repositories.
/install	NFS mount (xcat-mgmt:/install)	XCAT installation and provisioning directory.
/kuttam_fg	NFS (ibnfsgw:/srv/kuttam_fg)	Dedicated storage for the Kuttam team
/datasets	NFS (ibnfsgw:/srv/datasets)	Shared datasets available to all users.
/userfiles	NFS (ibnfsgw:/srv/userfiles)	User-provided datasets or project data.
/frozen	NFS (ibnfsgw:/srv/frozen)	Archived or frozen data for long-term retention.
/singularity	NFS (ibtmpfs:/srv/tmp)	Temporary space for Singularity container images.
/run/user/*	Temporary virtual memory (tmpfs)	Per-user runtime directories for sessions. Automatically cleared.