slow zpool import causes boot-archive failure
I have a data pool with lots of datasets and it's all on spinning rust, so importing it is legitimately quite slow. That's fine, but it apparently blocks a /dev/zfs ioctl which bootadm does for the boot-archive service, possibly making boot-archive time out and drop to maintenance. A workaround is to increase the timeout for the boot-archive service sufficiently, but that's not pretty.
I was under the impression that filesystem/local would do potentially expensive operations (such as importing non-root pools) and thus this could be solved by making the boot-archive service start sooner, but this doesn't seem to be the case: I tested making milestone/single-user depend on boot-archive: boot-archive still timed out, and in the maintenance shell I can see that the data pool has been imported.
Some more background at http://www.niksula.hut.fi/~ltirkkon/boot-archive-hang.txt and #illumos http://echelog.com/logs/browse/illumos/1392850800 (13:47 through 16:15 or so, my discussion with tsoome)