object: subdisks, plexes and volumes. The encoding for plexes and
subdisks no longer reflects the object to which they belong. The
super devices are high-order volume numbers. This gives vastly more
potential volumes (4 million instead of 256).
Tidy up comments.
Check for null rqgs. This continue to be reported, though I can't
work out why.
Correct formats for some error messages. Don't cast the value to
match the format.
Use microtime, not getmicrotime, for timing debug entries.
9ebe817222