Welcome to the Free Software contributions diary of Loïc Dachary. Although the posts look like blog entries, they really are technical reports about the work done during the day. They are meant to be used as a reference by co-developers and managers. Erasure Code Patents StreamScale.

Testing ceph-disk with block devices in docker

The Ceph command to setup a block device ( ceph-disk) needs to call partprobe after zapping a disk. The patch adding the partprobe call needs a block device to test that it works as expected. The body of the test requires root privileges:

 dd if=/dev/zero of=vde.disk bs=1024k count=200
 losetup --find vde.disk
 local disk=$(losetup --associated vde.disk | cut -f1 -d:)
 ./ceph-disk zap $disk

which is potentially dangerous for the developer machine. The run of the test is delegated to a docker container so that accidentally removing /var/run has no consequence. Although the test recompiles Ceph the first time:

main_docker "$@" --compile
main_docker "$@" --user root --dev test/ceph-disk.sh test_activate_dev

it will reuse the compilation results if run a second time. Unless there is a new commit in which case it will recompile whatever make decides. The ceph-disk-root.sh script is added to the list of scripts that are run on make check but will only be considered if –enable-docker has been given to ./configure and docker is available. Otherwise it will be silently ignored

check_SCRIPTS += \

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Ceph make check in docker

After Ceph is built from sources, unit and functional tests can be run with make check. Delegating the execution to a container makes it possible to:

  • keep working on the sources without disrupting the run
  • run functional tests that require root privileges without modifying the development environment
  • check various operating systems

The src/test/docker-test-helper.sh library can be used from the command line:

$ test/docker-test.sh --os-type ubuntu --os-version 14.04 make check &
$ test/docker-test.sh --os-type centos --os-version centos7 make check &

Each run uses a clone of the current repository and pulls from origin before executing the command. For instance, if running from /srv/ceph, the centos run will run make check in /srv/ceph-centos-centos7 which is bind mounted in the container. A possible workflow is:

  • work
  • commit
  • test/docker-test.sh make check which pulls the latest commits
  • keep working
  • check the make check output

In case an error happens, debugging starts by running a shell in the container

$ test/docker-test.sh --os-type ubuntu --os-version 14.04 --shell
remote: Counting objects: 10, done.
remote: Compressing objects: 100% (10/10), done.
remote: Total 10 (delta 8), reused 0 (delta 0)
Unpacking objects: 100% (10/10), done.
From /home/loic/software/ceph/ceph
 + 15046fe...8a39cad wip-9665 -> origin/wip-9665
HEAD is now at 8a39cad autotools: add --enable-docker

The first time test/docker-test.sh runs, it creates a docker images populated with the packages necessary to compile and run Ceph. This lowers the overhead to run a test in the container:

$ time test/docker-test.sh --os-type ubuntu --os-version 14.04 unittest_str_map
HEAD is now at 8a39cad autotools: add --enable-docker
Running main() from gtest_main.cc
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from str_map
[ RUN      ] str_map.json
[       OK ] str_map.json (1 ms)
[ RUN      ] str_map.plaintext
[       OK ] str_map.plaintext (0 ms)
[----------] 2 tests from str_map (1 ms total)

[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (1 ms total)
[  PASSED  ] 2 tests.

real	0m3.340s
user	0m0.071s
sys	0m0.046s
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Lowering Ceph scrub I/O priority

Note: the following does not currently work in Firefly because of http://tracker.ceph.com/issues/9677 . It has been backported to Firefly and will likely be in 0.80.8.

The disk I/O of a Ceph OSD thread scrubbing is the same as all other threads by default. It can be lowered with ioprio options for all OSDs with:

ceph tell osd.* injectargs '--osd_disk_thread_ioprio_priority 7'
ceph tell osd.* injectargs '--osd_disk_thread_ioprio_class idle'

All other threads in the OSD will be be (best effort) with priority 4 which is the default for daemons. The disk thread will show as idle:

$ sudo iotop --batch --iter 1 | grep 'ceph-osd -i 0' | grep -v be/4
 4156 idle loic        0.00 B/s    0.00 B/s  0.00 %  0.00 % ./ceph-osd -i 0 ..

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Posted in ceph | 3 Comments

Running Ceph with the tcmalloc heap profiler

When running a Ceph cluster from sources, the tcmalloc heap profiler can be started for all daemons with:

  ./vstart.sh -n -X -l mon osd

The osd.0 stats can be displayed with

$ ceph tell osd.0 heap stats
osd.0tcmalloc heap stats:------------------------------------------------
MALLOC:        6084984 (    5.8 MiB) Bytes in use by application
MALLOC: +       180224 (    0.2 MiB) Bytes in page heap freelist
MALLOC: +      1430776 (    1.4 MiB) Bytes in central cache freelist
MALLOC: +      7402112 (    7.1 MiB) Bytes in transfer cache freelist
MALLOC: +      5873424 (    5.6 MiB) Bytes in thread cache freelists
MALLOC: +      1290392 (    1.2 MiB) Bytes in malloc metadata
MALLOC:   ------------
MALLOC: =     22261912 (   21.2 MiB) Actual memory used (physical + swap)
MALLOC: +            0 (    0.0 MiB) Bytes released to OS (aka unmapped)
MALLOC:   ------------
MALLOC: =     22261912 (   21.2 MiB) Virtual address space used
MALLOC:           1212              Spans in use
MALLOC:             65              Thread heaps in use
MALLOC:           8192              Tcmalloc page size

See the Ceph memory profiling documentation for more information.

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Ceph development environment in Docker

The Docker package is installed with

sudo apt-get install docker.io

and the loic user is made part of the docker group to allow it to run containers.

$ grep docker /etc/group

The most popular ubuntu image collection reported by

$ docker search ubuntu | head -2
NAME    DESCRIPTION                 STARS ...
ubuntu  Official Ubuntu base image  715   ...

is pulled locally with

docker pull ubuntu

A container is created from the desired image (as found by docker images) is selected with:

docker run -v /home/loic:/home/loic -t -i ubuntu:14.04

the home directory is mounted into the container because it contains the local Ceph clone used for development. The user loic is recreated in the container with

adduser loic

and the necessary development packages are installed with

apt-get build-dep ceph
apt-get install libudev-dev git-core python-virtualenv emacs24-nox ccache

The state of the container is saved for re-use with

$ docker ps
CONTAINER ID        IMAGE               ...
2c694d6d5f90        ubuntu:14.04        ...
$ docker commit 2c694d6d5f90 ubuntu-14.04-ceph-devel

Ceph is then compiled and tested locally with

cd ~/software/ceph/ceph
./configure --disable-static --with-debug \
   CC='ccache gcc' CFLAGS="-Wall -g" \
   CXX='ccache g++' CXXFLAGS="-Wall -g"
make -j4
make check

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Posted in ceph | 1 Comment

OpenStack Upstream Training challenges

The OpenStack Upstream Training scheduled november 1st, 2014 in Paris will have a unprecedented number of participants and for the first time there is a shortage of Lego. In addition to the 80 pounds of spare parts (picture fourground), six new buildings have been acquired today (Tower Bridge, Sydney Opera, Parisian Restaurant, Pets Shop, Palace Cinema and Grand Emporium). They will be at Lawomatic for assembly form October 1st to October 31st. Anyone willing to participate please send me an email.

Once this first challenge is complete, the buildings will have to be transported to the Hyatt conference rooms where the training will take place. The rendez-vous point is 8am Lawomatic Saturday November 1st, 2014. Each of us will carefully transport a building (or part of it in the case of the Tower Bridge) in the subway. There will be coffee and croissants upon arrival :-)

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List the versions of OSDs in a Ceph cluster

List the versions that each OSD in a Ceph cluster is running. It is handy to find out how mixed the cluster is.

# ceph tell osd.* version
osd.0: { "version": "ceph version 0.67.4 (ad85ba8b6e8252fa0c7)"}
osd.1: { "version": "ceph version 0.67.5 (a60acafad6096c69bd1)"}
osd.3: Error ENXIO: problem getting command descriptions from osd.3
osd.6: { "version": "ceph version 0.72.2 (a913ded64099cfd60)"}
osd.7: { "version": "ceph version 0.72.1 (4d923874997322de)"}
osd.8: { "version": "ceph version 0.72.1 (4d923874997322de)"}
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HOWTO extract a stack trace from teuthology

When a teuthology test suite fails on Ceph, it shows in pulpito. For instance there is one failure in the monthrash test suite with details and a link to the logs. By removing the teuthology.log part of the link a directory listing shows all informations archived for this run are available.
In the example above the logs show:

client.0.plana34.stderr:+ ceph_test_rados_api_io
client.0.plana34.stdout:Running main() from gtest_main.cc
client.0.plana34.stdout:[==========] Running 43 tests from 4 test cases.
client.0.plana34.stdout:[----------] Global test environment set-up.
client.0.plana34.stdout:[----------] 11 tests from LibRadosIo
client.0.plana34.stdout:[ RUN      ] LibRadosIo.SimpleWrite
client.0.plana34.stdout:[       OK ] LibRadosIo.SimpleWrite (1509 ms)
client.0.plana34.stdout:[ RUN      ] LibRadosIo.ReadTimeout
client.0.plana34.stderr:Segmentation fault (core dumped)

That shows ceph_test_rados_api_io is running from the plana34 machine and core dumped and the remote/plana34/coredump subdirectory contains the corresponding core dump.
The teuthology logs show the repository from which the binary was downloaded (it was produced by gitbuilder).

echo deb http://gitbuilder.ceph.com/ceph-deb-precise-x86_64-basic/sha1/f5c1d3b6988bae5ffb914d2ac0b2858caeffe12c precise main | sudo tee /etc/apt/sources.list.d/ceph.list

and running this line on an Ubuntu precise 12.04 64bits as suggested by the name of the subdirectory precise-x86_64 will make the corresponding binary packages available. It is also possible to download them directly from the pool/main/c/ceph subdirectory. The packages that are suffixed with -dbg retain the debug symbols that are necessary for gdb to display an informative stack trace.
The ceph_test_rados_api_io binary is part of the ceph-test package and can be extracted with

$ dpkg --fsys-tarfile ceph-test_0.85-726-gf5c1d3b-1precise_amd64.deb | \
  tar xOf -  ./usr/bin/ceph_test_rados_api_io \
  > ceph_test_rados_api_io

and the stack trace displayed with

$ gdb /usr/bin/ceph_test_rados_api_io 1411176209.8835.core
(gdb) bt
#0  0x00007f541b95750a in pthread_rwlock_wrlock () from /lib/x86_64-linux-gnu/libpthread.so.0
#1  0x00007f541bd41341 in RWLock::get_write(bool) () from /usr/lib/librados.so.2
#2  0x00007f541bd2bbc9 in Objecter::op_cancel(Objecter::OSDSession*, unsigned long, int) () from /usr/lib/librados.so.2
#3  0x00007f541bcf1349 in Context::complete(int) () from /usr/lib/librados.so.2
#4  0x00007f541bdad5ea in RWTimer::timer_thread() () from /usr/lib/librados.so.2
#5  0x00007f541bdb149d in RWTimerThread::entry() () from /usr/lib/librados.so.2
#6  0x00007f541b953e9a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#7  0x00007f541b16a3fd in clone () from /lib/x86_64-linux-gnu/libc.so.6
#8  0x0000000000000000 in ?? ()
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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 then be run with

$ PYTHONPATH=pybind nosetests -v

and if only the TestIoctx.test_aio_read is of interest, it can be appended to the filename:

$ PYTHONPATH=pybind nosetests -v
test_rados.TestIoctx.test_aio_read ... ok

Ran 1 test in 4.227s

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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
Posted in Uncategorized | Leave a comment