Deploy Ceph on bare metal with Ansible
See what the Ceph client sees
The title is probably weird and misleading but I could not find better than this :). The idea here is to dive a little bit into what the kernel client sees for each client that has a RBD device mapped. In this article, we are focusing on the Kernel RBD feature.
Ceph enable the object map feature
The Hammer release brought the support of a new feature for RBD images called object map. The object map tracks which blocks of the image are actually allocated and where. This is especially useful for operations on clones like resize, import, export, flattening and size calculation since the client does not need to calculate where each object is located. The client will just look up on that table.
Ceph is complaining: too many PGs
Quick tip.
Ceph: activate RBD readahead
RBD readahead was introduced with Giant.
Ceph OSD daemon config diff
Quick tip.
Simply check the diff between the applied configuration in your ceph.conf and the default values on an OSD.
Ceph using Monitor key/value store
Ceph monitors make use of leveldb to store cluster maps, users and keys. Since the store is present, Ceph developers thought about exposing this through the monitors interface. So monitors have a built-in capability that allows you to store blobs of data in a key/value fashion. This feature has been around for quite some time now (something like 2 years), but haven’t got any particular attention since then. I even noticed that I never blogged about it :).
Ceph: manually repair object
Debugging scrubbing errors can be tricky and you don’t necessary know how to proceed.
Stretching Ceph networks
This is a quick note about Ceph networks, so do not expect anything lengthy here :). Usually Ceph networks are presented as cluster public and cluster private. However it is never mentioned that you can use a separate ne
Ceph: analyse journal write pattern
Simple trick to analyse the write patterns applied to your Ceph journal.