A/UX® Programmer's Reference Sections

zb(4) bzb(4)
FIELD DESCRIPTIONS
bzb magic
This field should always contain the magic number BZBMAG­
IC. If this field is not set to BZBMAGIC, the information in
the Block Zero Block should be treated as invalid.
bzb cluster
The value of this field determines the autorecovery(8)
cluster to which the associated disk partition belongs.
bzb type
This field identifies the type of NUX file system corresponding
to this Block Zero Block. Examples of NUX file systems
are regular file systems, autorecovery file systems,
and swap file systems (for these types, this field's values
would be FST, FSTEFS, and FSTSFS, respectively).
bzb inode
If nonzero, this field contains the number of the inode
corresponding to the bad block file in the corresponding partition
that will be used for bad blocking. If this field's value
is zero, there is no bad block inode/file allocated. This file is
made up of blocks that are bad (that is, blocks containing the
contents of this file are all bad). This keeps the bad blocks
out of the free list across f scks. This field is generally used
only for file systems that reside on physical disks that lack
hardware bad blocking or that support hardware bad blocking
but have run out of spare bad blocks. This field is not supported
for swap file systems.
The only supported values for this field are zero and one.
bzb root
When on, this bit indicates that the file system located on the
corresponding partition is a root file system.
bzb usr
When on, this bit indicates that the file system located on the
corresponding partition is a usr file system. If both this field
and the bzb _root are on, the file system is a root/usr file
system.
bzb crit
When on, this bit indicates that the file system located on the
corresponding partition is a critical file system. A critical file
system receives special treatment during the Bad Block por-
February, 1990 2
Revision C