Author Archives: Loic Dachary

Running python rados tests in Ceph

When Ceph is built from sources, make check will not run the test_rados.py tests. A minimal cluster is required and can be run from the src directory with: CEPH_NUM_MON=1 CEPH_NUM_OSD=3 ./vstart.sh -d -n -X -l mon osd The test can … Continue reading

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t540p touchpad disable mouse, keep buttons

To use the touchpad to click (but not to move the mouse) and keep using the trackpad for mouse movement: synclient AreaBottomEdge=1

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Ceph placement group memory footprint, in debug mode

A Ceph cluster is run from sources with CEPH_NUM_MON=1 CEPH_NUM_OSD=5 ./vstart.sh -d -n -X -l mon osd and each ceph-osd uses approximately 50MB of resident memory USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND loic 7489 1.7 … Continue reading

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Running node-rados from sources

The nodejs rados module comes with an example that requires a Ceph cluster. If Ceph was compiled from source, a cluster can be run from the source tree with rm -fr dev out ; mkdir -p dev CEPH_NUM_MON=1 CEPH_NUM_OSD=3 \ … Continue reading

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HOWTO test a Ceph crush rule

The crushtool utility can be used to test Ceph crush rules before applying them to a cluster. $ crushtool –outfn crushmap –build –num_osds 10 \ host straw 2 rack straw 2 default straw 0 # id weight type name reweight … Continue reading

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HOWTO test teuthology tasks

The Ceph integration tests run by teuthology are described with YAML files in the ceph-qa-suite repository. The actual work is carried out on machines provisioned by teuthology via tasks. For instance, the workunit task runs a script found in the … Continue reading

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What cinder volume is missing an RBD object ?

Although it is extremely unlikely to loose an object stored in Ceph, it is not impossible. When it happens to a Cinder volume based on RBD, knowing which has an object missing will help with disaster recovery.

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Tell teuthology to use a local ceph-qa-suite directory

By default teuthology will clone the ceph-qa-suite repository and use the tasks it contains. If tasks have been modified localy, teuthology can be instructed to use a local directory by inserting something like: suite_path: /home/loic/software/ceph/ceph-qa-suite in the teuthology job yaml … Continue reading

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Temporarily disable Ceph scrubbing to resolve high IO load

In a Ceph cluster with low bandwidth, the root disk of an OpenStack instance became extremely slow during days. When an OSD is scrubbing a placement group, it has a significant impact on performances and this is expected, for a … Continue reading

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Global shortcuts for emacs org-mode on Ubuntu

Let say F7 is bound, in emacs, to the org-clock-out function of Org Mode as a shortcut to quickly stop the current clock accumulating the time spent on a given task. (global-set-key (kbd “<f7>”) ‘org-clock-out) F7 can be sent to … Continue reading

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