We have noticed in testing that running multiple mdtest processes per node severely degrades unlink performance.

• Lustre mounted once per client; not multimount.
• shared directory case
  This can be seen at a wide range of node counts (5-128) and backends, to varying degrees.
  Interestingly scaling the client count up does not seem to have nearly the same negative performance impact; only the ppn seems to matter.

	total
nodes	jobs	unlink kops
8	8	11.4
8	16	9.7
8	32	8.6
8	64	7

We see the same issue with 1.8.6 clients against the server; we do not see it with 1.8.6 servers.