geo-rep: checkpointing

- gluster vol geo-rep M S conf checkpoint <LABEL|now>

  sets a checkpoint with LABEL (the keyword "now" is special,
  it's rendered to the label "as of <timestamp of current time>")
  that's used to refer to the checkpoint in the sequel.

  (Technically, gsyncd makes a note of the xtime of master's root
  as of setting the checkpoint, called the "checkpoint target".)

- gluster vol geo-rep M S conf \!checkpoint

  deletes the checkpoint.

- gluster vol geo-rep M S stat

  if status is OK, and there is a checkpoint configured, the checkpoint
  info is appended to status (either "not yet reached", or
  "completed at <timestamp of completion>").

  (Technically, the worker runs a thread that monitors / serializes /
  verifies checkpoint status, and answers checkpoint status requests
  through a UNIX socket; monitoring boils down to querying the xtime
  of slave's root and comparing with the target.)

- gluster vol geo-rep M S conf log-file | xargs grep checkpoint

  displays the checkpoint history. Set, delete and completion events
  are logged properly.

Change-Id: I4398e0819f1504e6e496b4209e91a0e156e1a0f8
BUG: 826512
Signed-off-by: Csaba Henk <csaba@redhat.com>
Reviewed-on: http://review.gluster.com/3491
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>

0 files changed, 0 insertions, 0 deletions