UBC Theses and Dissertations

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UBC Theses and Dissertations

RadFS - virtualizing filesystems Karollil, Anoop


Efficient disk space usage and quick deployment are important storage mechanism requirements in a virtualized environment. In a virtual machine farm, there is good potential for saving disk space as virtual machines are based off file system images that usually have a lot in common. Deploying virtual machines on demand should also be as quick as possible - close to or faster than the time taken in powering on and booting up a real machine. We introduce RadFS, a shared root filesystem for virtual machines based on copy-on-write semantics. Creating a new root file system for deploying a virtual machine is instantaneous, with the ability to base the new file system on the clone of a previous file system or a snapshot of an existing file system. Disk space us age efficiency is guaranteed initially by the COW semantics and later by transparent file-system ‘merges’ based on content hashing. Thus any file that is identical among the file systems of the various virtual machines hosted off our file system will be shared which leads to large savings in disk space with increased provisioning of virtual machines running similar operating systems or applications that use similar sets of files. Live instantaneous snapshots of existing file systems also ensure easy backups or new bases for other virtual machines. The filesystem or name space virtualization is implemented in user-space using FUSE and backed by a content hashing module to take care of merges.

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