Logical Volumem Management (LVM)
 

Hi there LQ peeps,
Can someone explain LVM in the simplest term? What is the benefits and advantage of using LVM? Thanks.

Hi there,

This here is a good place to start: http://tldp.org/HOWTO/LVM-HOWTO/whatisvolman.html

..and provides a pretty basic description of LVM in simple terms, and how/why one might want to use it.

Of course, if you have more specific questions, feel free to ask! :)

LVM takes all the storage you give to it, chops it up into homogeneous little pieces and then lets you make as many virtual storage devices you like out of all the little pieces.

Give it two 10GB drives and a 4GB drive and you have 24GB of space to assign however you want. e.g. one 15GB logical volume, one 2GB logical volume and 7GB of free space that you can add to either later on, or you could even make new LVs out of that 7GB whenever you want.

Personally, I've always stopped Fedora creating LVM on my system. Firstly, you need (or perhaps needed) a separate /boot partition, because grub couldn't understand logical volumes. Secondly, it just added to the general complexity of things, which is a Bad Thing. I assigned 10GB to / when I set up my system six years ago, and it's not run out yet; how much software could I find to install? For a server, with separate /var as well as /home, and the possibility of misjudging the assignment to one of them, it's a different question.

Thanks for the inputs guys. So LVM deals on storage. So is it better than RAID? Lets say I have 3x250g drives and i want to put it on a web server, so which is the best choice LVM or RAID?

LVM is not RAID. But nice thing about LVM: resize partitions if needed? Am I right?

LVM just gives you more flexibility to resize multiple partitions. RAID is a security device to ensure that your data is safe if a drive fails.

With 3 drives, a RAID 5 configuration means that your total storage capacity is only that of 2 drives, but if one of those drives dies, no data is lost.