I had the same thing happen to a run of mine once:
2015-07-01 14:26:50 INFO mon-relation-changed ^GCaution: invalid backup GPT header, but valid main header; regenerating
2015-07-01 14:26:50 INFO mon-relation-changed backup header from main header.
2015-07-01 14:26:50 INFO mon-relation-changed
2015-07-01 14:26:50 INFO mon-relation-changed Warning! Main and backup partition tables differ! Use the 'c' and 'e' options
2015-07-01 14:26:50 INFO mon-relation-changed on the recovery & transformation menu to examine the two tables.
2015-07-01 14:26:50 INFO mon-relation-changed
2015-07-01 14:26:50 INFO mon-relation-changed Warning! One or more CRCs don't match. You should repair the disk!
2015-07-01 14:26:50 INFO mon-relation-changed
I had the same thing happen to a run of mine once:
2015-07-01 14:26:50 INFO mon-relation- changed ^GCaution: invalid backup GPT header, but valid main header; regenerating changed backup header from main header. changed changed Warning! Main and backup partition tables differ! Use the 'c' and 'e' options changed on the recovery & transformation menu to examine the two tables. changed changed Warning! One or more CRCs don't match. You should repair the disk! changed
2015-07-01 14:26:50 INFO mon-relation-
2015-07-01 14:26:50 INFO mon-relation-
2015-07-01 14:26:50 INFO mon-relation-
2015-07-01 14:26:50 INFO mon-relation-
2015-07-01 14:26:50 INFO mon-relation-
2015-07-01 14:26:50 INFO mon-relation-
2015-07-01 14:26:50 INFO mon-relation-
16841 ? Ssl 0:00 /var/lib/ juju/tools/ unit-ceph- 1/jujud unit --data-dir /var/lib/juju --unit-name ceph/1 --debug juju/agents/ unit-ceph- 1/charm/ hooks/mon- relation- changed ceph-disk- prepare --fs-type xfs --zap-disk /dev/sdb
36054 ? S 0:02 \_ /usr/bin/python /var/lib/
38589 ? S 0:00 \_ /bin/sh /usr/sbin/
38592 ? S 0:00 \_ /usr/bin/python /usr/sbin/ceph-disk prepare --fs-type xfs --zap-disk /dev/sdb
38601 ? D 0:00 \_ /sbin/sgdisk --zap-all --clear --mbrtogpt -- /dev/sdb
It was stuck like this for hours. Nothing interesting in dmesg.
Since I was debugging potentially hardware disk issues on that node, I dismissed it.