LVM directly on whole SAN volume vs. LVM on single, whole SAN volume spanning partition

Question

I am wondering what the advantages and disadvantages of the following two scenarios are.

• LVM physical volume directly on SAN volume
  pvcreate /dev/sda

• LVM physical volume on a single partition, which is spanning the whole SAN volume
  parted /dev/sda -s -- mklabel gpt mkpart primary 0 -1
pvcreate /dev/sda1

I read in the LVM-Manual, that PV on the whole disk is not recommended because of management issues with other OSes that don't understand LVM-labels. But I am not sure, whether this really applies to SAN volumes in practice.

Furthermore I think partitioning adds another layer with possible problems, like device name changes of mapped devices on the partition device.

What is better practice?

Answer 1

Either method will work just fine and equivalently stable.

The partition-method is somewhat more intelligible by recovery utilities, though that is a minor concern. Anything based on a Linux (and probably *BSD) core will know how to handle a full-disk LVM setup, which includes pretty much every recovery tool I'd consider using on a broken Linux box. Tools designed for Windows recovery won't be able to handle full-disk LVM, though.

The SAN volume thing does require some consideration, but the big question to ask yourself is:

Is this volume ever going to be mounted by another device than this one?

Unless you're creating a cluster, the answer to that is probably "no" except in dire recovery circumstances. If you have to rebuild the boot/system volumes for some reason, chances are near certain you'll use the same OS you started with.

Full-disk LVM is just fine.

So is One-Partition LVM.

Use whichever feels better to you.