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How Linux Represents Storage DevicesBog'liq linuxbasicsforhackersHow Linux Represents Storage Devices
Linux uses logical labels for drives that are then mounted on the filesystem.
These logical labels will vary depending on where the drives are mounted,
meaning the same hard drive might have different labels at different times,
depending on where and when it’s mounted.
Originally, Linux represented floppy drives (remember those?) as fd0
and hard drives as hda. You will still occasionally see these drive repre-
sentations on legacy Linux systems, but today most floppy drives are gone
(thank goodness). Even so, old legacy hard drives that used an IDE or
E-IDE inte rface are still represented in the form hda. Newer Serial ATA
(SATA) interface drives and Small Computer System Interface (SCSI) hard
drives are represented as sda. Drives are sometimes split up into sections
known as partitions, which are represented in the labeling system with num-
bers, as you’ll see next.
When systems have more than one hard drive, Linux simply names
them serially by incrementing the last letter in alphabetical order, so the
first drive is sda, and the second drive is sdb, the third drive is sdc, and so
on (see Table 10-1). The serial letter after sd is often referred to as the major
number.
Table 10-1:
Device-Naming System
Device file
Description
sda
First SATA hard drive
sdb
Second SATA hard drive
sdc
Third SATA hard drive
sdd
Fourth SATA hard drive
Drive Partitions
Some drives can be split into partitions in order to manage and separate
information. For instance, you may want to separate your hard drive so
that your swap file, home directory, and / directory are all on separate
partitions—you might want to do this for a number of reasons, including
to share resources and to relax the default permissions. Linux labels each
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