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 /dev directory. For example, /dev/hda7 could be a partition on your master IDE disk. 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 SCSI device; partitions are sda1, sda2, … |
sdb | Second SCSI 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 fd1, fd2, …), usually mounted on /mnt/floppy |
Before a partition can hold files, it is “formatted” by writing a filesystem on it. A filesystem defines how files are ...