ecc(ADM) 19 June 1992 ecc(ADM) Name ecc, eccd - memory Error Correction Code (ECC) facility Syntax /etc/ecc Description The memory Error Correction Code (ECC) utilities periodically check RAM for single and double-bit errors to increase data integrity. This fea- ture is specific to Corollary smp RAM used in Corollary and Corollary- compatible systems. The ECC daemon: eccd The ECC daemon, or background program, scans the smp RAM checking for single bit errors. Single bit errors themselves are harmless and are au- tomatically corrected by hardware. However, if an additional bit is cor- rupted at the same location, a double bit error occurs and the system panics. The ECC daemon helps avoid double bit errors by informing the system administrator of existing single bit errors. Errors are reported via the system console and /usr/adm/messages. The system administrator should periodically check /usr/adm/messages for any single bit error notifica- tions and use the ecc utility to map the affected 4K page out of memory. The script that controls this process, /etc/idrc.d/ecc, is built manually using mkdev eccd. The /etc/idrc.d/ecc script is thereafter invoked auto- matically when the system enters multiuser mode. The ecc utility The administrator should check periodically for memory ECC errors. The ECC errors are displayed on the console and stored in /usr/adm/messages. The messages appear as follows: _________________________________________________________________________ found a single-bit error board=n bad_addr=xxxx _________________________________________________________________________ where n is the board number and xxxx is the address of the error. ECC errors are mapped and stored in a bad page table using the ecc util- ity. The main ecc menu appears as follows: _________________________________________________________________________ 1. Print Current Bad Memory Page Table 2. Add Entries to Current Bad Memory Page Table 3. Delete Entries from Current Bad Memory Page Table Enter your choice or `q' to quit: _________________________________________________________________________ Option 1 prints the current bad memory page table. Option 2 is used to add new entries to the table. Option 3 can be used to delete entires from the bad page table when memory boards or individual SIMMs have been replaced. You must reboot the system after modifying the bad page table for it to take effect. Note This utility works only with Corollary smp RAM and compatibles. Files /dev/ecc ECC device /etc/idrc.d/ecc ECC daemon startup script /etc/idsd.d/ecc ECC daemon shutdown script /etc/eccdata bad page table /etc/eccdpid deamon process ID Value added ecc is an extension of AT&T System V provided by The Santa Cruz Opera- tion, Inc.