Monthly Archives: May 2013

Ceph placement groups backfilling

Ceph stores objects in pools which are divided in placement groups. +—————————- pool a —-+ |+—– placement group 1 ————-+ | ||+——-+ +——-+ | | |||object | |object | | | ||+——-+ +——-+ | | |+————————————-+ | |+—– placement group … Continue reading

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Bio++: efficient, extensible libraries and tools for computational molecular evolution

Efficient algorithms and programs for the analysis of the ever-growing amount of biological sequence data are strongly needed in the genomics era. The pace at which new data and methodologies are generated calls for the use of pre-existing, optimized – … Continue reading

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Virtualizing legacy hardware in OpenStack

A five years old hardware is being decommissioned and hosts fourteen vservers on a Debian GNU/Linux lenny running a 2.6.26-2-vserver-686-bigmem linux kernel. The April non profit relies on these services (mediawiki, pad, mumble, etc. ) for the benefit of its … Continue reading

Posted in Essex, debian, openstack | 1 Comment

OpenStack Upstream University training

Upstream University training for OpenStack contributors include a live session where students contribute to a Lego town. They have to comply with the coding standards imposed by the existing buildings. More than fifteen participants created an impressive city within a … Continue reading

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Installing ceph with ceph-deploy

A ceph-deploy package is created for Ubuntu raring and installed with dpkg -i ceph-deploy_0.0.1-1_all.deb A ssh key is generated without a password and copied over to the root .ssh/authorized_keys file of each host on which ceph-deploy will act: # ssh-keygen … Continue reading

Posted in Raring, Ubuntu, ceph | 9 Comments

Disaster recovery on host failure in OpenStack

The host bm0002.the.re becomes unavailable because of a partial disk failure on an Essex based OpenStack cluster using LVM based volumes and multi-host nova-network. The host had daily backups using rsync / and each LV was copied and compressed. Although … Continue reading

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Minimal DNS spoofing daemon

When running tests in a controlled environment, it should be possible to spoof the domain names. For instance foo.com could be mapped into slow.novalocal, an OpenStack instance responding very slowly to simulate timeouts. A twisted based spoofing DNS reverse proxy … Continue reading

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