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Fault Tolerance and Availability* |
Solution Providers** |
Starting Price Estimates*** |
Description |
Advantages |
Disadvantages |
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Hardware and O/S based Disaster Tolerant, Assured Availability |
Compaq (formerly Tandem), Stratus |
Split-Site or Remote Site $80,000 to $250,000 not including network connectivity |
Multiple CPU-s that error check each other, error checking I/O channels and memory. This is the highest level of fault tolerance and error recovery you can get. |
This range of products includes super redundant computers that have no single point of failure. |
Can require custom software and special expertise for maintenance. |
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Software-based Disaster Tolerant, Assured Availability |
Marathon Technologies |
Split-site - $50,000, Remote‑site - $60,000, not including network connectivity |
Dual and Intel servers at each site with lock-step parallel execution of applications for Windows NT and Windows 2000. |
Continuous availability. Runs standard Windows applications, no special software code required. |
Remote site distance limitation of 1.5 kilometers Currently limited to two-processor systems. |
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Software-based and/or hardware‑based Disaster tolerant, High Availability |
Compaq, HP, Microsoft, Novell, Veritas |
Split-Site or Remote Site, $75,000 to $125,000 not including network connectivity |
Disaster tolerant dual-processor servers with redundant components and data replication between sites. Servers can be separated by up to 100 kilometers for some products and any distance for others. |
Servers can be located great distances apart. Many operating systems supported. Quad processors supported. |
Loss of application states during failover and failback. Failback can be lengthy if system is run in failed over mode for more than a day. |
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Software-based Assured Availability |
Marathon Technologies |
Single Site $40,000 |
Dual-PC systems with lock-step parallel execution of applications for Windows NT and Windows 2000. Provides recommended minimum level of fault tolerance for emergency response systems. |
All user sessions and data remain intact during failures and repairs, which are completely invisible to the users. Runs standard Windows applications, no special software code required. |
Currently limited to two-processor systems. No support for quad processor machines. |
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Software-based High Availability |
Compaq, HP, Microsoft, Novell, Veritas |
Single Site $30,000 ‑ $40,000 |
Dual processor server pair, primary server with standby server, using RAID storage and dual component redundancy. Recommended minimum level of fault tolerance for critical systems that run unattended at any time. |
Minimum down-time and minimum restoration time on loss of system functionality. User logins persist, users automatically notified of failover and failback. |
Loss of application states during failover and failback. Failback can be lengthy if system is run in failed over mode for more than a day. Loss of all unsaved data. |
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Cold backup server. Dual Power, RAID Disk Components, tape or disk backup system and UPS |
No special technology. Uses common hardware components. |
Single Site $15,000 ‑ $30,000 |
Switchover to backup system is manual. Hard drives may need to be moved from primary server to the backup server if real-time backup is not in use. Minimum recommendation for systems that are attended on a 24‑hour basis. |
Dual components mask power and disk drive failures. Backup server offsets possible long lead times for replacement parts. |
System is down for non-masked failures and requires manual switchover to backup server, manual switch back, with loss of user logons and all unsaved data. |
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Single PC with RAID hard drives, dual power supply, and cold replacement components. |
No special technology. Uses common hardware components. |
Single Site $4,000 to $6,000 depending upon cold or hot swappable components |
System must be manually restored. This is the lowest level of fault tolerance that should be accepted for any data based security application. This is the “low cost upgrade system” and the computer designed for 24-hour operation. |
Real-time backups prevent loss of current operating system and application data. In a complete system loss, all applications and operating system updates can be restored from backup. |
Non-RAID system will be down for the time it takes to restore from backup. |
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Non-RAID PC with cold replacement components, scheduled periodic backup. |
No special technology. |
Single Site $1,500 - $2,000 excluding tape backup |
This is the most common configuration for small and many medium sized security systems. |
Better than no backup at all. |
It may not be practical or even possible to restore the system entirely, if no printed record exists of transactions occurring after the last backup. |
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Non-RAID PC with cold replacement components, no tape backup, no UPS. |
No special technology. |
Single Site $600 - $1,000 |
This type of system is not suitable for any type of data based security application. |
None. |
Complete loss of data. Could take days or weeks to get back online. Complete restoration may not be possible due to data loss. |
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*Except as noted, backup tape drives, backup software and intelligent UPS systems are included in all solutions. |
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