Posted by: Anonymous
on August 23, 2007 02:03 AM
The two paragraphs are fine. LVM adds a layer of abstraction so that your OS can use "partitions" that do not have to correspond directly to the partitions on the disk. The descriptions of the terms seem fine to me - I have used LVM for a couple of years and think it is very useful. However, there are smart and silly ways to use it.
I don't think it is a good idea to mix several disks into a large volume group and dole out logical volumes from there - as other posters have said, you are creating the opposite of redundancy - introducing multiple points of failure.
I think LVM makes great sense for dividing a single disk much more flexibly than with multiple traditional partitions. At least the effect of that disk going down would not be any different. As for any performance penalty, I think the ability to resize partitions easily would usually be more than worth it.
The combination of LVM and RAID1 is, I think, a good choice for desktops. Hard drives are cheap, and the redundancy is good protection against data loss from drive failure (but of course does not protect against several other ways to lose one's data!). I usually partition two identical disks with a small partion, a large partition, and leave some empty space. The small partitions get mirrored into md0, which I use for /boot, and the large ones get mirrored into md0, which is the volume group for all of the rest of the partions. It seems to be a flexible and reliable arrangement, and it did indeed preserve my data flawlessly when one of the disks suddenly died.