A Fast Virtual Machine Storage Migration Technique Using Data Deduplication
Kazushi Takahashi, Koichi Sasada, Takahiro Hirofuchi · 2012
Abstract—In this paper, we proposed a fast virtual machine (VM) storage migration technique. Virtual machine storage migration can migrate entire VM states to other hosts, includ-ing VM disk images. It is widely used for cross-data-center load management. However, VM disk images generally have large file sizes (typically 1-30GB). Thus, storage migration was time-consuming. To address this problem, we introduce the deduplication technique into traditional VM storage migration. We focused on the fact that it is possible to return VMs from the new VM hosts. For example, a VM first migrates from host A to host B. Next, the VM returns from host B to host A. There will then be additional reusable disk pages in host A. Consequently, to expedite the operation, we only return to host A the disk pages that have been updated while in host B. We implement this idea to a QEMU/KVM (kernel virtual machine). To track the reusable disk pages, we developed a DBT (Dirty Block Tracking) mechanism and a new diff format to store the tracking result. In this paper, we discuss the design and implementation of our prototype. Our technique successfully reduced the transfer time for storage migration from 10 minutes to about 10 seconds in some practical workloads.