LVM vs RAID Home NAS Options

Question

From what I am reading it appears Logical Volume Management might be a better solution for what my plans currently involve.

My current setup consists of 3 1-TB drives all acting as some part of my home NAS. This works fine except files end up scattered throughout the entire NAS which is annoying.

The two options I can think of to correct this issue would be to either:

1. use RAID JBOD
2. use LVM.

I am leaning more to the side of LVM for no real reason. As it stands, I have enough spare storage that I can move everything off the drives, create the volumes and replace the data. This would be monotonous and very time consuming.

Does LVM offer some form of support where I can create one joined logical volume from the 3 physical volumes and automatically transport the data at the same time?

My other areas of interest are:

1. moving the physical drives from one location to another
2. being able to add drives at will.

Based off this what is my best choice in options?

Answer 1

I don't have any experience with JBOD. I can only offer you LVM solutions. With these LVM solutions, you will have to move existing data to some other storage before configuring the system because you need to create physical volume partitions. You can't do that on the fly without loosing data.

I have two solutions for your predicament:

Using only LVM:

+It gives you huge freedom with device manipulation (adding/removing)
Adding more storage: vgextend my_volume_group /dev/hdcY
Removing storage: pvmove /dev/hdaX && vgreduce my_volume_group /dev/hdaX
-no redundancy

RAID5 + LVM

-You will get less space for those three drives: 2000 GB compared to 3000GB combined on LVM only
+Speed gain: 2x read speed, no write speed gain
+Fault tolerance: 1-drive failure

Reducing the number of drives would mean that you need to reduce the raid arrays\, and not logical volumes. You would effectively have 1 device as your physical volume, and that would be the raid array.
LVM is still good if you want to add additional (maybe different) raid arrays into the mix, instead of working with just one drive array. It is, however, advised that you use similar raid sets. Like 2xRAID5, or 2xRAID0 or 2xRAID10, and that disks/raid sets have similar characteristics in terms of performance.