Violin: A Framework for Extensible Block-Level Storage
The quality of virtualization mechanisms provided by a storage system affects storage management complexity and storage efficiency, both of which are important problems of modern storage systems. We argue that current storage systems provide limited flexibility and extensibility in virtualizing, managing and accessing storage.
In this work we address this problem by proposing Violin, a virtualization framework that allows easy extensions of block-level storage stacks. Violin allows (i) developers to provide new virtualization functions and (ii) storage administrators to combine these functions in storage hierarchies with rich semantics. Violin makes it easy to develop new virtualization functions by providing support for (i) hierarchy awareness and arbitrary mapping of blocks between virtual devices, (ii) an easily extensible I/O command set, (iii) explicit control over both the request and completion path of I/O requests, and (iv) persistent metadata management.
In this paper we present Violin’s architecture and we show how simple Violin modules can be combined in more complex hierarchies. Finally, we demonstrate hierarchies with advanced virtualization functionality that is difficult to implement with monolithic drivers.
Keywordsstorage virtualization multi-layered storage block-level I/O
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