Re: Beginners partition advice

On March 4, 2009 09:42, in alt.os.linux.suse, houghi
(houghi@xxxxxxxxxxxxxxxxxx) wrote:

Lester wrote:
Thanks Houghi, the warning is noted. I certainly remain a beginner so
it's not something I want to meddle with at this early stage. Since I
didn't install Linux on the machine I'm keen to see how it was
installed and the impression I get is partitions are the first thing
you encounter.

On a lower lever you will encounter partitions. They are much less
intrusive to the _user_ then on Windows. On Windows the user often needs
to know what is on C: and what is on D: and so on.

Linux does not work that way. It starts at / and from there it is a
tree. Each directory could be a seprate partition and each subdirectory
again.

The reason there are three partions is because of the following reason:
1) Swap needs to be seperate as that uses a different specific file
system.
2) / and /home used to be the same. Hoever when you do a new
installation, you will most likely reformat everything. When /home is on
a seperate partition, withy a new installation, you won't loose your
personal data.
[snip]

It is worth noting that, in a Linux system as in a Windows system, multiple
partitions are not necessary. They do, however, provide some advantages
that are not available with single partition systems.

WRT your first point, Linux swap does not /need/ to reside in a partition of
it's own. Like Windows, you can implement the linux virtual memory paging
facility as a /file/ within an existing filesystem. The swapon(8) ("man 8
swapon") command that your Linux startup executes early on tells Linux
where to find it's vm paging space (the "swap file" or "swap partition");
this command can point Linux at a named file, if you want. In any case,
Linux real memory management is sufficiently different from Windows real
memory management that, for sufficient real memory (about 1Gb or more) you
often don't /need/ a swapfile or swap partition.

WRT your second point, for most casual users, the separation of /home from
the root fs is probably the only good reason to have multiple partitions.
However, for "power users", and those who build and administer Linux
systems in multi-user environments (even a standalone webserver would fit
this later category), there are many reasons to partition. I once wrote an
incomplete list of reasons, which I post below:

* Make intelligent use of disk space by reserving space for future]
expansion of your filesystems

* To perform optimization of disk access resources by placing heavily used
disk resources closer to optimum seek point of the disk

* To impose restrictions on the size of certain directory subtrees
(i.e. /tmp or /var/spool/lpd) to ensure that they do not grow beyond
certain preset sizes.

* To facilitate backup and recovery by enabling volume backups as well as
directory tree/subtree backups

* To reduce the time taken by the boot up filesystem check, by reducing the
amount of filesystem checked at any one time, and by permitting the
filesystem check to parallelize it's operations.

* To facilitate upgrades by ensuring that the upgrade process doesn't
delete or reformat certain directory subtrees (like /home
or /var/spool/news) as part of the installation/upgrade process

* To restrict online access to certain directory subtrees (i.e. the boot
partition ) by ensuring that they are mounted "read-only" or not mounted
at all when they are not needed.

* To provide alternate (or recovery) directory subtrees, by offering
offline space for image archives of critical directory subtrees, or by
providing space for alternate versions of the directory subtrees (i.e.
a "recovery" root fs)

* To provide alternate filesystem formatting (journal fs vs unjournaled
fs), to meet the needs of the use of the filesystem (i.e. use journalling
filesystems where recovery is required (like / or /home), and
non-journalling filesystems where recovery is unnecessary (like /tmp
or /var/tmp).

* To provide alternate filesystem blocksizes (1K, 4K, etc) to meet the
needs of the use of the filesystem (i.e. smaller blocksizes for
filesystems that store many small files vs larger blocksizes for
filesystems that store large files).

Just my 2 cents worth :-)
--
Lew Pitcher

Master Codewright & JOAT-in-training | Registered Linux User #112576
http://pitcher.digitalfreehold.ca/ | GPG public key available by request
---------- Slackware - Because I know what I'm doing. ------


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