Be conservative: renew subscription once half the interval has expired.
Do not reuse sub expiration to control hunting.
Signed-off-by: Sage Weil <sage@newdream.net>
The monitor cluster is responsible for managing cluster membership
and state. The monitor client handles what minimal interaction
the Ceph client has with it: checking for updated versions of the
MDS and OSD maps, getting statfs() information, and unmounting.
Signed-off-by: Sage Weil <sage@newdream.net>