[jamii]

http://research.cs.wisc.edu/adsl/Publications/ibench-sosp11....

> We analyze the I/O behavior of iBench, a new collection of productivity and multimedia application workloads. Our analysis reveals a number of differences between iBench and typical file-system workload studies, including the complex organization of modern files, the lack of pure sequential access, the influence of underlying frameworks on I/O patterns, the widespread use of file synchronization and atomic operations, and the prevalence of threads. Our results have strong ramifications for the design of next generation local and cloud-based storage systems.

> The iBench tasks also illustrate that file systems are now being treated as repositories of highly-structured “databases” managed by the applications themselves. In some cases, data is stored in a literal database (e.g, iPhoto uses SQLite), but in most cases, data is organized in complex directory hierarchies or within a single file (e.g., a .doc file is basically a mini-FAT file system). One option is that the file system could become more application-aware, tuned to understand important structures and to better allocate and access these structures on disk. For example, a smarter file system could improve its allocation and prefetching of “files” within a .doc file: seemingly non-sequential patterns in a complex file are easily deconstructed into accesses to metadata followed by streaming sequential access to data.