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I-CASH: Intelligently Coupled Array of SSD and HDD. Jin Ren and Qing Yang Dept. of Electrical, Computer, and Biomedical Engineering University of Rhode Island , Kingston, RI 02881 High Performance Computer Architecture (HPCA), 2011 IEEE 17th International Symposium on. I-CASH.
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I-CASH: Intelligently Coupled Array of SSD and HDD Jin Ren and Qing Yang Dept. of Electrical, Computer, and Biomedical Engineering University of Rhode Island, Kingston, RI 02881 High Performance Computer Architecture (HPCA), 2011 IEEE 17th International Symposium on
I-CASH • Speed gap between CPUs and disk I/O systems • I-CASH exploits advancements of SSD, multi-core processors and HDD
Advantages of SSD/MCP/HDD • Fast read performance of SSD • High computing power of multicore processor • Reliable/durable/sequential write performance of HDD
Content Locality • Large files and collections of files show strong content locality with large amount of data redundancy • thousands of similar virtual machines running on servers • Virtual machine image sprawl
Heatmap creation • Each 4KB block is divided into 8 512-bytes sub-blocks • Signature is the sum of 4 bytes in a sub-block at offsets 0, 16, 32, and 64
When does similarity detection starts? • When a block is first loaded • After every 2,000 I/Os • I-CASH checks the 4,000 blocks from the beginning of an LRU queue
Numerical Results and Evaluations • Sysbench • 1% reference blocks • 85% delta blocks • 14 %independent blocks
RUBiS benchmark • Over 90% of the requests are read requests • Which limits the write performance advantage of I-CASH over Fusion-io