CMAX Technical Support

What is a Group Format Error (GFE)?

A GFE in a multivalue database is a representation of corruption within the database or file system. The system should not be used in a production environment without resolving the GFE condition.

What causes Group Format Errors?

GFEs are almost always caused by an improper shutdown of the system or a hardware failure in the disk subsystem. Multivalue systems use sophisticated virtual memory management techniques in the manipulation of data. Since virtual memory is in the system volatile RAM or random access memory of the CPU, a power-failure, unexpected system reset, memory parity error, or other hardware error can cause the system RAM to be erased without being properly written back to the hard drive. This situation can cause missing data in the file system which is reported by the system as a GFE.

How can I check a system for the existence of Group Format Errors?

The best way to scan a system for GFEs is to execute a process that will read the entire file system, such as a backup process might do. One way to execute an appropriate test is as follows:

TCL command to check for GFEs:

1. From the SYSPROG Menu, type XX <enter>
2. At the TCL prompt (>), type SAVE SYSTEM SYSTEM (DFSY <enter>

The system will then scroll through the system and account files reporting any Group Format Errors.

There is also is system-level reporting mechanism for checking for GFEs:

1. From the SYSPROG Menu, type XX <enter>
2. At the TCL prompt (>), type LIST-GFE-LOG <enter>
   
   

What should I do if a GFE exists on my system?

When a GFE is encountered on a multivalue database system, the GFE handler is involved. The GFE handler accepts several commands to resolve the GFE situation. Unfortunately, all of the commands (except 'X' to exit) result in the GFE being repaired by truncation or other methods resulting in the loss of data. The most common resolution method is to enter the command 'F' (fix the GFE) in the GFE handler, then restore the affected file from some backup source (FILE-SAVE or Host System). You may need to contact CMAX Technical Support for guidance in resolving a GFE situation.

How can I prevent Group Format Errors?

• Always protect the power source of your CPU by using an uninterruptible power supply (UPS). Note that CMAX requires the use of a properly-sized UPS on all supported systems. Most UPS models have an interface that communicates with the Operating System, allowing a controlled shutdown before the standby battery life is exhausted. The utilization of this type of interface will further reduce exposure to power related GFE problems.

• Always use proper shutdown procedures before resetting or powering down a multivalue system (Native, Unix, or Windows NT/2000). NEVER hit the system reset button or the power switch on the system CPU without first executing the multivalue system shutdown procedure from the Utilities Menu.

• Minimize wide fluctuations in the temperature of the environment where the CPU is located (especially problematic in the spring and fall). Excessive heat is the enemy of electrical components. See the manufacturer's recommendations for environmental considerations and ventilation requirements. Keep the area around the CPU clean and dust free to minimize the amount of particulate drawn into the CPU case by the exhaust fans.

• Remember that power surges and electrical interference may enter the CPU from sources other that the AC power connection. Lightning and power surges may enter through unprotected modem lines, terminals, printers, and networked workstations. Protect all connected devices and lines with quality surge and lightning protectors.