Compaq ProLiant 1200 Manual page 9

ECG0094/1197
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For greater reliability and fault tolerance, Compaq is developing a number of products that will
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implement Fibre Channel technology. Fibre Channel is a key technology for the system-to-storage
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interconnect (high-speed box-to-box communications) and the serial drive interface (high-
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performance disk systems) in delivering bigger, faster, better network data storage solutions. It
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provides opportunity for the integration of primary and secondary storage as well as shared storage
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between multiple servers.
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Developed by committees accredited by the American National Standards Institute to define new
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. . . . protocols for flexible information transfer, Fibre Channel is an industry-standard interconnect and
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high-performance serial I/O protocol that is media independent and supports simultaneous transfer
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. . . . of many different protocols. The use of fiber optics for transmission results in extremely low error
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rates. Furthermore, Fibre Channel incorporates a powerful encoding scheme and a strong cyclic
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redundancy check on each message frame, ensuring data integrity.
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. . . . Fibre Channel is now the only standard that can handle the traditional channel and network
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functions simultaneously on the same port. It supports simultaneous hot plug, allowing removal or
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insertion of multiple drives from an active loop without affecting throughput. For more information
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about Fibre Channel, refer to technology brief ECG008.0897, Strategic Direction for Compaq
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Fibre-Channel-Attached Storage.
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Compaq's DLT drives use advanced linear recording technology, a highly accurate tape guide
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system, and an adaptive control mechanism to provide high-capacity, high-duty cycle backups. The
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drives have four parallel tracks and heads; if one track/head unit fails, the others can continue the
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backup. Up to three track/head units can fail without putting a drive out of operation.
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A powerful Reed Solomon ECC featuring a 64-bit cyclical redundancy check on each 4 KB of
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media data, end-to-end 16-bit cyclical redundancy check on each record overlapped with parity
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from the SCSI bus, and internal parity checking on the cache buffer are used to help ensure data
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integrity. This results in a theoretical average hard error rate of only one in 10
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. . . . one undetected error in 10
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verify data by performing a read operation after each write command and by automatically re-
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. . . . recording data if a recording error is detected.
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. . . . The Tape Drive Status Alert feature notifies the system administrator, through Compaq Insight
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Manager, if something goes wrong in preparation for a backup. The Reread/Rewrite Threshold
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Alert feature notifies the system administrator if predetermined reread/rewrite levels are exceeded,
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preventing drive failure from extreme reread/rewrite activity. For more information about Compaq
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DLT drives, see technology brief 395A/0197, DLT Hardware Technology.
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Compaq DLT Arrays help protect critical data through regular automated backups of large servers,
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networks, and enterprises in a process that maintains the absolute integrity of the data. The DLT
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Array houses up to four DLT drives (driven by Cheyenne ARCserve 6.0 or JETserve 3.3), which
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enable fast image backups in redundant array of independent tapes (RAIT) configurations (similar
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to disk drive RAID configurations). Backup applications that do not support RAIT configurations,
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such as Seagate Backup Exec and Legato Networker, can also be run with Compaq DLT Arrays.
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When used in RAIT configuration, the DLT Array stripes data across the drives and creates parity
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records, which can be used to rebuild data on a failed tape/drive. If one drive goes down during a
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. . . . backup, the others continue
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Drive repair or replacement can be scheduled when the backup is complete.
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Tape manageability features are included in Compaq Insight Manager. The DLT Array is covered
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. . . . by Compaq's Pre-Failure Warranty. For more on the DLT Array, see technology brief 395A/0197,
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DLT Hardware Technology.
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bits of data. As an added reliability measure, Compaq DLT drives
as many as three drives can fail without compromising the backup.
Eliminating Single Points of Failure (cont.)
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bits, with less than