LVM or not ?
 

Hi all.

During my surfing on different forums, i have seen many ppl saying they dont use LVM. In my view, LVM does a great job, allowing you to expand partition over multiple drives. So if ppl say they dont use LVM, what they actually mean ?

1) They dont need to expand their partition ?
2) Or is there any alternative available ?

I mean, if i want to increase the size of my /home partition, if i am not using LVM, i cant do by simply adding another drive right ??

You can use unionfs (or aufs) to adding another drive. There's raid0 too.

I agree, LVM has many useful features (the ability to increase the size of partitions, the ability to encrypt the root file system, etc) that aren't accessible without it. Fedora seems to be the king of LVM at this point, because the Fedora installer uses LVM to create an encrypted root FS. I have no idea why people are against it.

WIth the size of disks these days, it's probably option 1, but as troop pointed out, there are other options if all you want is a mechanism to span volumes.

Though LVM also provides a mechanism for spanning, it's not it's primary purpose. If anyone is using it only for that then IMO they're missing out, but from the posts I've seen on these forums over the years, there are many people who seem to be using it badly.

Another of LVM's useful features is snapshotting. Snapshotting allows verify-after-backup and a short down time for services that keep altering files when running such as virtual machines. For example:

1. Stop VMs
2. Create LVM snapshot
3. Start VMs
4. Verify backup
5. Drop LVM snapshot

I'm one of those that stoped Fedora using LVM when I first installed. I simply don't need it (/home is only 40% full after 6 years), so I avoided adding unnecessary complication.

I recently installed both CentOS 5.5 and Debian Squeeze and was puzzled by their default of using all the disk (except for a small /boot) for LVM and then assigning all the LVM space to / (no other file systems except /boot).

Perhaps I'm misunderstanding something but that seems to give all the complexity of LVM and none of the benefits ... :scratch:

I may be slightly off in my knowledge so if I am please correct me, but I think I am correct when I say, LVM is useful because you don't need to devote your entire hard drive to partitions for LVM and (this one I am not totally sure about but I think is true), you would be able to alter sizes of your partitions even after install. I don't believe LVM allows for redundant content so that could be risky.

./Randy