<a href="http://www.mail-archive.com/misc@openbsd.org/msg82811.html" rel="nofollow">http://www.mail-archive.com/misc@openbsd.org/msg82811.html</a><p>Setting the HPA (immediately after secure erase) ensures that some LBAs always remain unallocated and should give the GC more candidate erase blocks to work with, increasing random write performance. Or at least that's how I understand it.