HP JFS 3.3 and HP OnLineJFS 3.3 VERITAS File System 3.3 System Administrator's Guide

Chapter 2 65
Disk Layout
The VxFS Version 2 Disk Layout
bit being on. The length of the free inode map is 2K for file systems with
1K or 2K block sizes and is equal to the block size for file systems with
larger block sizes.
Extended Inode Operations Map The extended inode operations
map keeps track of inodes on which operations would remain pending for
too long to reside in the intent log. The extended inode operations map is
in the same format as the free inode map. To prevent the intent log from
wrapping and the transaction from getting overwritten, the required
operations are stored in the affected inode. This map is then updated to
identify the inodes that have extended operations that need to be
completed. This map allows the fsck utility to quickly identify which
inodes had extended operations pending at the time of a system failure.
The length of the extended inode operations map is 2K for file systems
with 1K or 2K block sizes and is equal to the block size for file systems
with larger block sizes.
Link Count Table
The link count table (LCT) contains a reference count for each inode in
the associated fileset. This reference count is identical to the
conventional link field of an inode. Each LCT entry contains the actual
reference count for the associated fileset inode. The link count field in an
inode itself is set to either 0 or 1, and the actual number of links is stored
in the LCT entry for the associated fileset inode.
The link count table can be reconstructed using the inode list, so it is not
replicated.
The current layout only uses the LCT for inodes in the attribute fileset.
The LCT supports quick updates of the link count for structural fileset
inodes.
Current Usage Table
The current usage table (CUT) is a file that contains usage related
information for each fileset. The information contained in the CUT
changes frequently and is not replicated. The information in the CUT
can, however, be reconstructed using the inode list if the CUT is
damaged.
The CUT file contains one entry per fileset (see Figure 2-9, “Current
Usage Table (CUT) File”). The CUT entry for a given fileset contains
information such as the following: