[linux-lvm] how to determine minimum partition size based on PV size

[Joe Harvell]

I need to reduce the size of an existing PV so that I can shrink the
partition it resides on an reclaim the storage.  I have already shrunk
the file systems and done an lvreduce.

I have three questions:

1. Is the value of the '--setphysicalvolumesize' argument to the
'pvresize' command the size the physical volume (contents and metadata)
will occupy on disk after the operation?  Or is it the specifying the
new capacity of the PV to hold data?
2. How do I determine the minimum size I can specify to pvreduce and
still have all of the original contents of the PV in the newly sized PV?
3. How do I determine the size the newly modified PV occupies on disk so
that I can reduce the partition it lives on to its minimum size?