Synchronized Disk Interleaving
IEEE Transactions on Computers
A case for redundant arrays of inexpensive disks (RAID)
SIGMOD '88 Proceedings of the 1988 ACM SIGMOD international conference on Management of data
Efficient placement of audio data on optical disks for real-time applications
Communications of the ACM
An Evaluation of Multiple-Disk I/O Systems
IEEE Transactions on Computers
Disk arm movement in anticipation of future requests
ACM Transactions on Computer Systems (TOCS)
Improving Disk Performance Via Latency Reduction
IEEE Transactions on Computers
Practical prefetching techniques for parallel file systems
PDIS '91 Proceedings of the first international conference on Parallel and distributed information systems
Algorithmic Studies in Mass Storage Systems
Algorithmic Studies in Mass Storage Systems
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
Object Placement in Parallel Hypermedia Systems
VLDB '91 Proceedings of the 17th International Conference on Very Large Data Bases
SODA '02 Proceedings of the thirteenth annual ACM-SIAM symposium on Discrete algorithms
Using fractional primal-dual to schedule split intervals with demands
ESA'05 Proceedings of the 13th annual European conference on Algorithms
Using fractional primal-dual to schedule split intervals with demands
Discrete Optimization
| Hi-index | 0.00 |
The common model for analyzing seek distances on a magnetic disk uses a continuous approximation in which the range of motion of the disk arm is the interval [0,1]. In this model, both the current location of the disk arm and the location of the next request are assumed to be points uniformly distributed on the interval [0,1] and therefore the expected seek distance to service the next request is 1/3. In many types of databases including scientific, object oriented, and multimedia database systems, a disk service request may involve fetching very large objects which must be transferred from the disk without interruption. In this paper we show that the common model does not accurately reflect disk arm movement in such cases as both the assumption of uniformity and the range of motion of the disk arm may depend on the size of the objects. We propose a more accurate model that takes into consideration the distribution of the sizes of the objects fetched as well as the disk arm scheduling policy. We provide closed form expressions for the expected seek distance in this model under various assumptions on the distribution of object sizes and the capability of the disk arm to read in both directions and to correct its position before the next read is performed.