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Enabled by its grid architecture and unique redundancy scheme, the IBM XIV system provides unprecedented reliability. These qualities immunise the system against any single failure and reduce the risk of double failure significantly below the industry standard. The XIV system achieves its unmatched reliability through various means: Active-active N+1 redundancy – All of the IBM XIV system disk drives, modules, switches, and UPS units are fully redundant, ensuring high reliability and excellent performance. 30-minute rebuild time (or less!) - The XIV system uses a revolutionary redundancy scheme, in which each disk is split into small pieces, and each piece is mirrored on a different disk. As a result, when a disk does fail, all disks in the system participate in the rebuild. After a failure of a 1 TB drive on a fully utilized IBM XIV system, the system is exposed to double disk failure for a rebuild time of just 30 minutes or less. This time significantly reduces (by orders of magnitude) the risk of double disk failure, especially in comparison with competitors storage systems. Rebuilds real data only - The IBM XIV system performs rebuild on only that data which has been allocated to volumes and, of the allocated data, only on data that has actually been written. Competitors storage systems typically perform disk rebuild at the block level, rebuilding the failed disk completely and taking the full length of time this requires. Self-healing upon module failure - The IBM XIV system employs self-healing even after module failure by initiating a rebuild process and returning to full redundancy. The failed module is replaced only after redundancy has resumed, protecting the system from technician errors. Consistent performance through any failure – The IBM XIV system maintains the same high performance level through any failure.
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