Fast, Inexpensive Content-Addressed Storage in Foundation Sean Rhea,∗ Russ Cox, Alex Pesterev∗ Meraki, Inc
Fast, Inexpensive Content-Addressed Storage in Foundation Sean Rhea,∗ Russ Cox, Alex Pesterev∗ Meraki, Inc. MIT CSAIL Abstract particular operating system, itself depending on a particu- lar hardware configuration. In the worst case, a user in the Foundation is a preservation system for users’ personal, distant future might need to replicate an entire hardware- digital artifacts. Foundation preserves all of a user’s data software stack to view an old file as it once existed. and its dependencies—fonts, programs, plugins, kernel, Foundation is a system that preserves users’ personal and configuration state—by archiving nightly snapshots digital artifacts regardless of the applications with which of the user’s entire hard disk. Users can browse through they create those artifacts and without requiring any these images to view old data or recover accidentally preservation-specific effort on the users’ part. To do so, deleted files. To access data that a user’s current environ- it permanently archives nightly snapshots of a user’s en- ment can no longer interpret, Foundation boots the disk tire hard disk. These snapshots contain the complete soft- image in which that data resides under an emulator, al- ware stack needed to view a file in bootable form: given lowing the user to view and modify the data with the same an emulator for the hardware on which that stack once programs with which the user originally accessed it. ran, a future user can view a file exactly as it was. To limit This paper describes Foundation’s archival storage the hardware that future emulators must support, Foun- layer, which uses content-addressed storage (CAS) to re- dation confines users’ environments to a virtual machine.
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