Hitachi 9960, 9900 Series manual High Performance Back-endDesign, High-speed Back-endDesign

High Performance Back-end Design

High-speed Back-end Design

New Hitachi high-performance back-end drives are available with the Lightning 9900™ Series. The drives are attached via Fibre Channel – Arbitrated Loops (FC-AL). Eight 100MB/sec FC-AL connect to dual ported drives for each ACP pair. With four configured ACP pairs installed (at 800 MB/sec per ACP pair) that’s 3.2GB/sec total back-end bandwidth to the physical drives.

Each FC-AL path is driven with a dedicated processor and a Data Recovery and Regeneration (DRR) circuit. This is in contrast to the Hitachi Freedom 7700E™, where two of the FW-SCSI-2 paths in the back end were shared through a single processor and single DRR circuit. (See also Figure 2). Basically, the number of processors and DRR circuits in the back end of the Lightning 9900 Series has increased to 32 (for the Lightning 9960™), compared to the 7700E’s 16. The diagram of a Lightning 9900™ Series ACP pair is shown in Figure 17 and Figure 18. Figure 19 illustrates all four ACP pairs with 32 back-end disks per array group.

The Lightning 9900™ Series uses advanced algorithms for managing performance of ACP pairs.

New Fibre Channel Disk Drives

The back-end performance of the Lightning 9900™ Series is enhanced with the introduction of a new dual ported/dual active Fibre Channel disk drive technology. These disk drives are specially designed and built by Hitachi Ltd. for the Lightning 9900™ Series. The disks are in a 3-inch form factor with capacities available in 18GB and 73GB spinning at 10,025RPM. These are all high-density disks (HDDs) spinning at high RPMs. The transfer rates with these new disks are approaching 60MB/sec. Higher sectors per physical track means less head movement and more data transferred per rotation, even when compared to the 7700E 15GB disks, which spin at 12,030RPM.

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Figure 17 – Functional diagram of a Lightning 9900™ Series ACP pair.

The Lightning 9900™ Series uses custom Hitachi high availability disk drives.

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