KVM Forum 2015

VM users often expect the storage backend to do more than just store data, such as the ability of creating live backups. In order to use some of these features, it is necessary to use the qcow2 format for storing the VM disk data. However, qcow2 incurs a performance penalty over just storing the data as a raw file. Therefore, users always face the choice of trading features for performance. This presentation will briefly touch why there are important reasons for using qcow2, and then focus on its performance, the reasons for said penalty, and what can be done and is being done to try to overcome it.