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Real-time disk scheduling algorithm allowing concurrent I/O requests

Staelin, Carl; Amir, Gidi; Ben-Ovadia, David; Dagan, Ram; Melamed, Michael; Staas, Dave
HP Laboratories


Keyword(s): real-time disk scheduling, storage systems, operating systems, RAID

Abstract: We present a real-time disk scheduling algorithm, Concurrent DS-SCAN (CDS-SCAN), which maximizes throughput for modern storage devices by allowing concurrent I/O requests at the device whenever possible. Past real-time disk scheduling algorithms allowed a single request at a time to go to the storage device, which dramatically reduces the utilization and throughput for modern storage devices, such as RAID arrays and disks with efficient positional-aware scheduling algorithms. We extended the DS-SCAN algorithm so that it can properly account for multiple outstanding I/O requests and guarantee real-time constraints for both outstanding and pending real-time requests. We demonstrate CDS-SCAN's performance on a storage array.

11 Pages

External Posting Date: October 21, 2009 [Fulltext]. Approved for External Publication
Internal Posting Date: October 21, 2009 [Fulltext]

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