HP ProLiant 1200 Eliminating Single Points of Failure and Enabling Rapid Recov - Page 9

ECG0094/1197 Eliminating Single Points of Failure (cont.) ... For greater reliability and fault tolerance, Compaq is developing a number of products that will implement Fibre Channel technology. Fibre Channel is a key technology for the system-to-storage interconnect (high-speed box-to-box communications) and the serial drive interface (highperformance disk systems) in delivering bigger, faster, better network data storage solutions. It provides opportunity for the integration of primary and secondary storage as well as shared storage between multiple servers. Developed by committees accredited by the American National Standards Institute to define new protocols for flexible information transfer, Fibre Channel is an industry-standard interconnect and high-performance serial I/O protocol that is media independent and supports simultaneous transfer of many different protocols. The use of fiber optics for transmission results in extremely low error rates. Furthermore, Fibre Channel incorporates a powerful encoding scheme and a strong cyclic redundancy check on each message frame, ensuring data integrity. Fibre Channel is now the only standard that can handle the traditional channel and network functions simultaneously on the same port. It supports simultaneous hot plug, allowing removal or insertion of multiple drives from an active loop without affecting throughput. For more information about Fibre Channel, refer to technology brief ECG008.0897, Strategic Direction for Compaq Fibre-Channel-Attached Storage. Compaq's DLT drives use advanced linear recording technology, a highly accurate tape guide system, and an adaptive control mechanism to provide high-capacity, high-duty cycle backups. The drives have four parallel tracks and heads; if one track/head unit fails, the others can continue the backup. Up to three track/head units can fail without putting a drive out of operation. A powerful Reed Solomon ECC featuring a 64-bit cyclical redundancy check on each 4 KB of media data, end-to-end 16-bit cyclical redundancy check on each record overlapped with parity from the SCSI bus, and internal parity checking on the cache buffer are used to help ensure data integrity. This results in a theoretical average hard error rate of only one in 1017 bits, with less than one undetected error in 1030 bits of data. As an added reliability measure, Compaq DLT drives verify data by performing a read operation after each write command and by automatically rerecording data if a recording error is detected. The Tape Drive Status Alert feature notifies the system administrator, through Compaq Insight Manager, if something goes wrong in preparation for a backup. The Reread/Rewrite Threshold Alert feature notifies the system administrator if predetermined reread/rewrite levels are exceeded, preventing drive failure from extreme reread/rewrite activity. For more information about Compaq DLT drives, see technology brief 395A/0197, DLT Hardware Technology. Compaq DLT Arrays help protect critical data through regular automated backups of large servers, networks, and enterprises in a process that maintains the absolute integrity of the data. The DLT Array houses up to four DLT drives (driven by Cheyenne ARCserve 6.0 or JETserve 3.3), which enable fast image backups in redundant array of independent tapes (RAIT) configurations (similar to disk drive RAID configurations). Backup applications that do not support RAIT configurations, such as Seagate Backup Exec and Legato Networker, can also be run with Compaq DLT Arrays. When used in RAIT configuration, the DLT Array stripes data across the drives and creates parity records, which can be used to rebuild data on a failed tape/drive. If one drive goes down during a backup, the others continue  as many as three drives can fail without compromising the backup. Drive repair or replacement can be scheduled when the backup is complete. Tape manageability features are included in Compaq Insight Manager. The DLT Array is covered by Compaq's Pre-Failure Warranty. For more on the DLT Array, see technology brief 395A/0197, DLT Hardware Technology.