OpenStack and Backup
Doing backups in the Cloud is not an easy task. In this article I will try to answer some frequently asked questions.
OpenStack summit Vancouver talks: Ceph and OpenStack upgrades
Self promotion ahead :) For the next OpenStack summit I have submitted two talks.
OpenStack: perform consistent snapshots with Qemu Guest Agent
A while back, I wrote an article about taking consistent snapshots of your virtual machines in your OpenStack environment. However this method was really intrusive since it required to be inside the virtual machine and to manually summon a filesystem freeze. In this article, I will use a different approach to achieve the same goal without the need to be inside the virtual machine. The only requirement is to have a virtual machine running the qemu-guest-agent.
OpenStack and Ceph: RBD discard
Only Magic Card player might recognize that post picture :) (if you’re interested)
I have been waiting for this for quite a while now. Discard, also called trim (with SSD), is a space reclamation mechanism that allows you to reclaim unused blocks on a disk. RBD images are sparse by default, this means that the space they occupy increase the more you write data (opposite of preallocation). So while writing on your filesystem you might end up to the end of your device. On the Ceph side, no one knows what is happening on the filesystem, so we actually end up with fully allocated blocks… In the end the cluster believes that the RBD images are fully allocated. From an operator perspective, having the ability to reclaim back the space unused by your running instances is really handy.
OpenStack Cinder with Ceph under the hood
What’s happening under the hood while playing with Cinder and Ceph? Answer table :-).
OpenStack: disable a compute node during its first bootstrap
For operationnal reasons, you might not want to automatically make your compute node available. With the following flag, during its first bootstrap the compute node will register itself to the service list. However it will be disabled, so virtual machines can not be scheduled on it:
enable_new_services=False
OpenStack configure VM migrate nova SSH
Just a reminder for me :D.
OpenStack: import existing Ceph volumes in Cinder
This method can be useful while migrating from one OpenStack to another.
OpenStack Glance: import images and convert them directly in Ceph
Ceph, to work in optimal circumstances requires the usage of RAW images. However, it is painful to upload RAW images in Glance because it takes a while. Let see how we can make our life easier.
OpenStack Glance: disable cache management while using Ceph RBD
The OpenStack documentation often recommends to enable the Glance cache while using the default store file, with the Ceph RBD backend things are slightly different.