16. Appendix: More on partitioning
After several questions on what partitioning
really is, I'll just quote an answer I gave in
a mail once.
Okay, here goes:
In an operating system you need several different filesystems
for several different applications. For example, you need a
swap filesystem because your main memory can't hold all
information the operating system needs, so some of it has to be
temporary written to disk. You may also need some special
filesystem from which the machine reads the operating system
when you switch it on. Finally, you need of course one or more
filesystems to store the operating system program files and your
user files. It may be a good idea to put these in different
places (ie. on different filesystems) in case you have to
reinstall the operating system, but don't want to scratch all
your work.
The best thing is maybe to have all these filesystems on
different disks. But one has seldom more than one or two disks
in a computer. So what we do is to slice up the disk(s) in
several slices (partitions) and use the slices for several
filesystems. Then the operating system mounts the filesystems
together to one single file tree, so it is easy to access the
files.
(Other operating systems, like MS-DOS and NT use
some other technology: They do not bind the slices
together to one file tree, but keeps them separate
as "stations". What is the best scheme? You figure!)
Here a thought example with one 2GB disk on a 7248:
The mount point shows where in the file tree a
filesystem is mounted.
Partition Size Type Mountpoint Bootable
----------------------------------------------------------------
/dev/sda1 10MB 41 (PReP Boot) (Not mounted) yes
/dev/sda2 150MB 82 (Linux Swap) (Not mounted) -
/dev/sda3 1840MB 83 (Linux ext2) / (Root partition) -
|
This would give a bootprompt command like this:
If you want, you could add own partitions for important
directories like /home, /boot, /var, /usr/local and
so on. Here is an other example with two disks,
actually my own configuration with two disks:
Partition Size Type Mountpoint Bootable
----------------------------------------------------------------
/dev/sda1 20MB 43 (PReP Boot) (Not mounted) yes
/dev/sda2 133MB 82 (Linux Swap) (Not mounted) -
/dev/sda5 930MB 83 (Linux ext2) / (Root partition) -
/dev/sdb1 315MB 83 (Linux ext2) /home -
/dev/sdb2 770MB 83 (Linux ext2) /usr/local -
|
This would give a bootprompt command like this:
Before you ask:
ext2 is Linux' standard filesystem
GNU/Linux often uses the old partition scheme from MS-DOS. This means
that if there are more than 4 partitions on one disk, one uses
an extended partition (sda4) that may hold several logical
partitions (sda5, sda6, sda7, ...)
Yes, my partition scheme is a bad one. My root partition was
filled up in a couple of weeks or so. Don't use it. It is an
example only.
Hope this clears up some things.
Take our 
