The Dell MD3460 controller array can support up to 120 drives with an MD3060e expansion tray attached. Single drive capacities have been steadily increasing, but transfer speeds have remained fairly constant. As a result, RAID6 rebuild times can exceed 24hrs when using 4TB drives. This is the main reason for choosing Dynamic Disk Pools over RAID6 - lower rebuild times are possible since the RAID parity data is distributed spread across all drives in the pool. For the latest Fermi storage configuration, we are benchmarking eight 15-disk DDP volumes on each 120-drive MD3460+MD3060e storage config. Both arrays are dual-attached to a failover pair of servers (fermi-gpfs01,2). In a failover scenario, one machine could serve all sixteen DDP volumes.
The sgpdd-survey benchmark simulates performs parallel I/O using raw unformatted LUNs. The tests spawn and an increasing number of threads (thr) that write and read to an increasing number of concurrent regions (crg). As the tests progress, I/O becomes more random. This set of tests transfer data in The transfer operations use 1MB records/chunks (rsz).
One 15-disk LUN
Max write ~1GB/sec , Max read ~1GB/sec
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