Live Disk Operations: Juggling Data and Trying to go Unnoticed
Storage management is one of the hardest parts of running a virtualized data center. Storage is slow but large; storage holds precious data and at the same time it is subject to disastrous failures. Due to low speed and large size, it is often impossible to keep virtual machines offline while doing maintenance on the host's disks. Yet, virtualization promises to minimize your downtime and even to help you delegate maintenance tasks. In order to reconcile these two opposites, live disk operations let you perform maintenance while the virtual machine is running. Support for these operations is a recent addition to the QEMU/KVM storage subsystem; this talk will cover the various tasks that QEMU can perform live, how it does them, and why you shouldn't be afraid of it.