Performance analysis of the RIO multimedia storage system with heterogeneous disk configurations

HO is a mtdtimedia object server which manages a set of parfld disks and supports red-time data d&very tith statisticrd dday guarantees. MO uses random data aRocation on diik< combiied with partial rephcation to achieve load balance and high performance b this paper we amdyze the perform~ce of NO when the set, of disks used to store data blocks is not homogeneous, having both tierent bandwidths and Merent storage capacities. The basic problem to be addr~<sed for heterogeneous configurations is that, on a~erage, the &action of the load &ect ed to each disk is pr~ portiond to the amount of data stored on it, which may not. be proportion~ to the disk bandtidth. This may cause some disks to be overloaded, with long queues and delays, even though bandwidth is av~able on other disks. This r~ dnces the system throughput or increases the dday bonnd that. can be guarateed. ~ problem @es whenever the bandtidth to space ratio (BSR) is not uniform across W disks. b NO tfis problem is addra=sed by rephcatiug a fraction of dat a blocks. Rephcation Wows some of the load of the diiks tith smder BSR to be redirected to the disks tith higher BS~ reducing or -sting the long range load imbalance, depmding on the amount of rep~cation.