NAME

bbutil − manipulate an st506 device bad block list

SYNOPSIS

/sbin/bbutil [ device_name ]

DESCRIPTION

bbutil enters the bad block management program. 
 
This allows the superuser to manipulate the bad block list stored on st506 devices. The bad block list facilitates the replacement of damaged st506 sectors (256 bytes). Any reference to a damaged sector will be automatically routed to the replacement sector by the st506 device driver.

The specified device name must be that of a raw st506 device (default "/dev/rst0" if no device name is given).  The program appends characters onto the given device name to access specific partitions. The characters "A" and "B" refer to fixed system partitions. 

A partition 7: complete disc (encompasses all other partitions). 

B partition 6: ADFS and bad block list. 

bbutil refers to device sectors by their cylinder, track and sector addresses. This is the form output by the device driver when a disc failure occurs. 

bbutil automatically loads and displays the current stored bad block list when invoked.  bbutil allows the user to add ‘a’ and delete ‘d’ sector replacements. It is the users responsibility to save any modifications onto the disc by use of the ‘w’ command.  bbutil will prompt the user when exiting if modifications have not been saved. 

The bad block structure contains validity checks to ensure data integrity. If any of these checks fail the program will notify the user and ask if they want to continue. Writing a bad block list to the device automatically ensures all the validity checks.  Two copies of the bad block list are kept on the disc for security. 

The driver loads the bad block list from the device when it is initialised. If the bad block list is updated the system must be re-booted (see “reboot”) before the modifications are registered. 

Note: It is imperative that any modifications to the list are verified before re-booting. If sectors within system areas are mapped out without valid data being placed in the replacement sector then the system may fail to re-boot. “fsck” should be executed after the bad block list has been updated to ensure the integrity of the filesystem structures. 
 

SEE ALSO

reboot(8), fsck(8), bblist(5), ptable(5)

4th Berkeley Distribution  —  Jan  1, 1989