Mass StorageJonathan GeislerApril 5, 2006Jonathan Geisler Mass StorageDisk managementi.e., Low-level detailsFormattingPhysicalLogicalPartitioningBoot block(s)Bad blocksForwarding (sector sparing)Sector slippingJonathan Geisler Mass StorageSwap-space managementSuffers from fragmentationLocationFile inside file systemSeparate partitionAllocationAt process creationAs neededJonathan Geisler Mass StorageRAIDMore disks = more failuresRedundancy allowsProblem fixes without data lossIncreased throughput or transfer rateAccomplished viaMirroringError correcting codes (e.g., Hamming)Parity bitsJonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageRAID levelsTraditional0None. Striping1Mirror2ECC3Bit-interleaved4Block-interleaved5Distributed blo c k-interleaved6P + Q parity0+1 or 1+0 combination of levels 0 and 1Jonathan Geisler Mass StorageTertiary storageMediaRemovable disksTapesRobotic tape librariesFuturistic?HolographicMEMSJonathan Geisler Mass StorageHow does the OS deal with removable media?APIDisks unchangedTapes only get raw I/OFile names left to userCan manage robotic jukebox directly like any other deviceStaging old files to tapeNOT utilizing taps for virtual memoryJonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass StorageWhat to consider . . .1SpeedBandwidthLatency2ReliabilityHard drive > optical storage > tapeHead crashes are near fatal3CostTraditionally: DRAM > disk > tapeNow: DRAM > tape ≥ disk!!!Jonathan Geisler Mass