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43 lines
1.4 KiB
ReStructuredText
43 lines
1.4 KiB
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===================
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RBD Replay
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===================
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.. index:: Ceph Block Device; RBD Replay
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RBD Replay is a set of tools for capturing and replaying Rados Block Device
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(RBD) workloads. To capture an RBD workload, ``lttng-tools`` must be installed
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on the client, and ``librbd`` on the client must be the v0.87 (Giant) release
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or later. To replay an RBD workload, ``librbd`` on the client must be the Giant
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release or later.
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Capture and replay takes three steps:
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#. Capture the trace. Make sure to capture ``pthread_id`` context::
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mkdir -p traces
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lttng create -o traces librbd
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lttng enable-event -u 'librbd:*'
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lttng add-context -u -t pthread_id
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lttng start
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# run RBD workload here
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lttng stop
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#. Process the trace with `rbd-replay-prep`_::
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rbd-replay-prep traces/ust/uid/*/* replay.bin
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#. Replay the trace with `rbd-replay`_. Use read-only until you know
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it's doing what you want::
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rbd-replay --read-only replay.bin
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.. important:: ``rbd-replay`` will destroy data by default. Do not use against
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an image you wish to keep, unless you use the ``--read-only`` option.
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The replayed workload does not have to be against the same RBD image or even the
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same cluster as the captured workload. To account for differences, you may need
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to use the ``--pool`` and ``--map-image`` options of ``rbd-replay``.
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.. _rbd-replay: ../../man/8/rbd-replay
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.. _rbd-replay-prep: ../../man/8/rbd-replay-prep
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