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The ADvanced Systems Laboratory (ADSL)
Publication abstract

Snapshots in a Flash with ioSnap

Sriram Subramanian, Swaminathan Sundararaman, Nisha Talagala, Fusion-io, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau, Department of Computer Sciences, University of Wisconsin-Madison


Snapshots are a common and heavily relied upon feature in storage systems. The high performance of flash-based storage systems brings new, more stringent, requirements for this classic capability. We present ioSnap, a flash optimized snapshot system. Through careful design exploiting common snapshot usage patterns and flash oriented optimizations, including leveraging native characteristics of Flash Translation Layers, ioSnap delivers low-overhead snapshots with minimal disruption to foreground traffic. Through our evaluation, we show that ioSnap incurs negligible performance overhead during normal operation, and that common-case operations such as snapshot creation and deletion incur little cost. We also demonstrate techniques to mitigate the performance impact on foreground I/O during intensive snapshot operations such as activation. Overall, ioSnap represents a case study of how to integrate snapshots into a modern, well-engineered flash-based storage system.

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