Tuesday, May 24, 2011

Partitions - Type and Sizes For Linux

- it's best to put /usr, /var, /tmp, and /home each on their own partitions separate from the / partition.
- /usr/local partition if you plan to install many programs that are not part of the Debian distribution.

- Putting /tmp on its own partition is a good idea.
(Beware that the default path for Brasero to create iso file is /tmp)
(All files in /tmp will be purge every time debian restart)

- If your machine will be a mail server, you might need to make /var/mail a separate partition.
A mail server getting spammed with e-mail can easily fill a partition.
If you made /var/mail a separate partition on the mail server, most of the system will remain working even if you get spammed.
- postgres data files?
- apt cache

contain static data
The usage space of /usr in my desktop is ~3G.

Arch: 32MB (https://wiki.archlinux.org/index.php/Beginners%27_Guide)
Ubuntu: About 500 MB is recommended. (http://www.linuxbsdos.com/2010/10/12/ubuntu-10-10-manual-disk-partitioning-guide/)
Redhat: Minimum size = 250 MB (http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/s2-diskpartrecommend-x86.html)
Debian: the boot partition should be ext2 or ext3. (http://forums.citrix.com/thread.jspa?threadID=284981)

- By putting swap on a separate partition, Linux can make much more efficient use of it.
It is possible to force Linux to use a regular file as swap, but it is not recommended.

On 32-bit architectures (i386, m68k, 32-bit SPARC, and PowerPC), the maximum size of a swap partition is 2GB.Ref: https://help.ubuntu.com/11.04/installation-guide/amd64/apcs03.html

Swap should equal 2x physical RAM for up to 2 GB of physical RAM, and then an additional 1x physical RAM for any amount above 2 GB, but never less than 32 MB.

So, if:

M = Amount of RAM in GB, and S = Amount of swap in GB, then

If M < 2
    S = M *2
    S = M + 2

Using this formula, a system with 2 GB of physical RAM would have 4 GB of swap,
while one with 3 GB of physical RAM would have 5 GB of swap.
Creating a large swap space partition can be especially helpful if you plan to upgrade your RAM at a later time.

For systems with really large amounts of RAM (more than 32 GB) you can likely get away with a smaller swap partition (around 1x, or less, of physical RAM).
Ref: http://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-diskpartitioning-s390.html

File Systems (Partition Type)
- if your partition is larger than around 6GB, choose ext3 as your partition type.
- Ext2 partitions need periodic file system integrity checking, and this can cause delays during booting when the partition is large.

Fedora 14 >
ext4 for /boot, / is mandatory. (shown during installation)

https://ext4.wiki.kernel.org/index.php/Frequently_Asked_Questions >> Break 32000 subdirectory limit

As of 27-8-2011, VirtualBox still have some problems on ext4.

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