Document Type



Master of Science (MS)


Computer Science

First Advisor's Name

Cyril Orji

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Raimund Ege

Third Advisor's Name

Nagarajan Prabhakaran

Fourth Advisor's Name

Dawn Holmes


Electronic data processing, Backup processing alternatives

Date of Defense



Unequaled improvements in processor and I/O speeds make many applications such as databases and operating systems to be increasingly I/O bound. Many schemes such as disk caching and disk mirroring have been proposed to address the problem. In this thesis we focus only on disk mirroring. In disk mirroring, a logical disk image is maintained on two physical disks allowing a single disk failure to be transparent to application programs. Although disk mirroring improves data availability and reliability, it has two major drawbacks. First, writes are expensive because both disks must be updated. Second, load balancing during failure mode operation is poor because all requests are serviced by the surviving disk. Distorted mirrors was proposed to address the write problem and interleaved declustering to address the load balancing problem. In this thesis we perform a comparative study of these two schemes under various operating modes. In addition we also study traditional mirroring to provide a common basis for comparison.





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