[Lustre-discuss] Shirinking the mdt volume

[Bob Ball]

When we set up our mdt volume, lo these many years past, we did it with 
a 2TB volume.  Overkill.  About 17G is actually in use.

This is a Lustre 1.8.4 system backed by about 450TB of OST on 8 
servers.  I  would _love_ to shrink this mdt volume to a more manageable 
size, say, 50GB or so, as we are now in a down time before we upgrade to 
Lustre 2.1.6 on SL6.4.  I have taken a "dd" of the volume, and am now in 
the process of doing
getfattr -R -d -m '.*' -P . > /tmp/mdt_ea.bak
after which I will do a
tar czf {backup file}.tgz --sparse
/bin/tar is the SL5 version tar-1.20-6.x86_64.  This supports the 
--xattrs switch.  So, a choice here, should I instead use the --xattrs 
switch on the tar, or should I use --no-xattrs since the mdt_ea.bak will 
have all of them?

What are my prospects for success, if I restore that tar file to a 
smaller volume, then apply the attr backup, before I upgrade?

Answers and advice are greatly appreciated.

bob