= lvm - logical volume manager =

on Debian Lenny and Wheezy


== General Remarks ==

It is very useful to split up partitions for various reasons.
An extra partition should be used if one of these points is true:

1.) the size of data is extraordinary large (double the size of other data)
2.) the data needs a special handling for backup (e.g. video, mp3)
3.) the data has another importance (can be lost, e.g. trash, src, download)
4.) the files sizes are completely different (larger, e.g. video or smaller e.g. mail)
5.) the data has another lifetime (e.g. rootfs will live shorter then /usr/local or /home)
6.) the data is used for a lightweight container which does not have quotas


A typical non-trivial setup might have 10 different partitions.
To handle the number of partitions efficent, lvm should be used.

== Snapshots ==

sudo lvcreate -l100%FREE -s -n mysnap /dev/mylvm/mylvm
sudo lvremove /dev/mylvm/mylvm

== Prepartion ==

(to re-read partion table, use: hdparm -z)

apt-get install lvm2

setup raid on hard discs

mdadm --create ...

pvcreate /dev/md0
vgcreate lvm-raid -s 16M /dev/md0

-s (PhysicalExtentSize) is 4MB by default.
lvm2 does not have restrictions nor will the I/O
be slowed down, but the tools will be slower.


http://www.gagme.com/greg/linux/raid-lvm.php
http://www.linuxhaven.de/dlhp/HOWTO/DE-LVM-HOWTO-1.html
http://www.pro-linux.de/t_system/lvm.html