From 70e1a5dcbb1b817a935782037f9a2b11d12f4d53 Mon Sep 17 00:00:00 2001 From: Adam Crume Date: Mon, 1 Dec 2014 20:44:02 -0800 Subject: [PATCH] doc: Document RBD Replay Signed-off-by: Adam Crume --- doc/rbd/rbd-replay.rst | 37 +++++++++++++++++++++++++++++++++++++ doc/rbd/rbd.rst | 1 + 2 files changed, 38 insertions(+) create mode 100644 doc/rbd/rbd-replay.rst diff --git a/doc/rbd/rbd-replay.rst b/doc/rbd/rbd-replay.rst new file mode 100644 index 0000000000000..cc21ac9eb69d0 --- /dev/null +++ b/doc/rbd/rbd-replay.rst @@ -0,0 +1,37 @@ +=================== + RBD Replay +=================== + +.. index:: Ceph Block Device; RBD Replay + +RBD Replay is a set of tools for capturing and replaying Rados Block Device (RBD) workloads. +To capture an RBD workload, ``lttng-tools`` must be installed on the client, and ``librbd`` on the clent must be the Giant release or later. +To replay an RBD workload, ``librbd`` on the clent must be the Giant release or later. + +Capture and replay takes three steps\: + +1) Capture the trace. Make sure to capture ``pthread_id`` context:: + + mkdir -p traces + lttng create -o traces librbd + lttng enable-event -u 'librbd:*' + lttng add-context -u -t pthread_id + lttng start + # run RBD workload here + lttng stop + +2) Process the trace with `rbd-replay-prep`_:: + + rbd-replay-prep traces/ust/uid/*/* replay.bin + +3) Replay the trace with `rbd-replay`_. Use read-only until you know it's doing what you want:: + + rbd-replay --read-only replay.bin + +.. important:: ``rbd-replay`` will destroy data by default. Do not use against an image you wish to keep, unless you use the ``--read-only`` option. + +The replayed workload does not have to be against the same RBD image or even the same cluster as the captured workload. +To account for differences, you may need to use the ``--pool`` and ``--map-image`` options of ``rbd-replay``. + +.. _rbd-replay: ../../man/8/rbd-replay +.. _rbd-replay-prep: ../../man/8/rbd-replay-prep diff --git a/doc/rbd/rbd.rst b/doc/rbd/rbd.rst index 4105362d8a88a..a2c7c219bcab4 100644 --- a/doc/rbd/rbd.rst +++ b/doc/rbd/rbd.rst @@ -55,6 +55,7 @@ devices simultaneously. Manpage rbd-replay-prep <../../man/8/rbd-replay-prep> Manpage rbd-replay <../../man/8/rbd-replay> librbd + RBD Replay .. _RBD Caching: ../rbd-config-ref/ -- 2.47.3