Linux Pocket Guide, 2nd Edition

Disks and Filesystems

df	Display available space on mounted filesystems.
mount	Make a disk partition accessible.
umount	Unmount a disk partition (make it inaccessible).
fsck	Check a disk partition for errors.
sync	Flush all disk caches to disk.

Linux systems can have multiple disks or disk partitions. In casual conversation, these are variously called disks, partitions, filesystems, volumes, even directories. We’ll try to be more accurate.

A disk is a hardware device, which may be divided into partitions that act as independent storage devices. Partitions are represented on Linux systems as special files in (usually) the directory /dev. For example, /dev/sda7 could be a partition on your hard drive. Some common devices in /dev are:

hda	First IDE bus, master device; partitions are hda1, hda2, ...
hdb	First IDE bus, slave device; partitions are hdb1, hdb2, ...
hdc	Second IDE bus, master device; partitions are hdc1, hdc2, ...
hdd	Second IDE bus, slave device; partitions are hdd1, hdd2, ...
sda	First block device, such as SCSI, SATA, USB, or Firewire hard drives; partitions are sda1, sda2, ...
sdb	Second block device; partitions are sdb1, sdb2, ... Likewise for sdc, sdd, ...
ht0	First IDE tape drive (then ht1, ht2, ...) with auto-rewind
nht0	First IDE tape drive (then nht1, nht2, ...) without auto-rewind
st0	First SCSI tape drive (then st1, st2, ...)
scd0	First SCSI CD-ROM drive (then scd1, scd2, ...)
fd0	First floppy drive (then ...