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  Quantum Atlas 10K II Review 
  May 14, 2001, 10:00am EDT 

Ultra160 Overview, Data Integrity

By: Sander Sassen

Because data integrity and reliability are equally critical to overall system performance, SCSI is the only viable option for mission critical applications. Today Ultra160 SCSI is gradually replacing UW and U2W SCSI as the standard in servers and workstations. To strengthen data reliability and reliability Ultra160 SCSI offers both Cyclic Redundancy Checking (CRC) as well as Domain Validation to ensure these needs are met.

Error checking is imperative for high-speed operations; Ultra160 SCSI's CRC technology ensures that all data sent reaches its intended destination in the correct form. Each data block sent contains extra bytes that let the receiving device, regardless of its class, harddisk, CD-RW or otherwise, validate its contents. This is especially important in an electrically noisy environment, where electromagnetical fields may corrupt the data block. The CRC technology ensures that the data block is checked and verified prior to being processed; if it fails, a request is made to resend.

Domain Validation intelligently verifies system configuration. During the boot cycle, or any time a new SCSI device is connected, the host adapter tests for the maximum speed that device is capable of. This process is very similar to the way modems communicate to determine highest possible baud rate. As a result no user data is sent until a suitable speed is negotiated and a proper connection made.

Domain Validation offers more to SCSI technology than just setting reliable speed limits. It also monitors performance, picks up bottlenecks and helps predict possible problems, thus improving performance and better maintaining the SCSI bus.

Naturally, Ultra160 takes full advantage of all the commands built into the current SCSI standard. For example, SCAM, SCSI Configured AutoMatically, lets devices negotiate with the host adapter and not only set up features such as termination and synchronous or asynchronous communication, but also SCSI ID and busspeed. Tagged Command Queuing optimizes transfer speed by re-ordering blocks of data moving across the SCSI bus, giving smaller blocks priority. Disconnect/Reconnect allows disconnect from the SCSI bus while performing a complex task, and reconnection when done. This allows other devices free access to the SCSI bus and thus speeds up overall data transfer.

1. Introduction
2. Ultra160 Overview, Data Integrity
3. Ultra160 Overview, The SCSI vs. IDE Discussion
4. Quiet Drive Technology, QDT
5. Data protection System, DPS
6. Shock Protection System, SPS
7. Shock Protection System, Cont.
8. Quantum Atlas 10K II
9. Benchmark Setup
10. Benchmark Results
11. Benchmark Evaluation
12. Technical Support
13. Conclusion

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  Product Ratings 
Quantum Atlas 10K II
Performance: 8/10
Quality: 8/10
Features: 8/10
Documentation: 6/10
Price: 6/10
Overall Rating: 7/10

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