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

Chapter 2 61
Disk Layout
The VxFS Version 2 Disk Layout
• time of last access
• time of last modification
• pointers to the extents that contain the file’s data
There are up to ten direct extent address size pairsper inode. Each direct
extent address indicates the starting block number of a direct extent;
direct extent sizes can vary. If all of the direct extents are used, two
indirect address extents are available for use in each inode. The first
indirect address extent is used for single indirection, where each entry in
the extent indicates the starting block number of an indirect data extent.
The second indirect address extent is used for double indirection, where
each entry in the extent indicates the starting block number of a single
indirect address extent. Each indirect address extent is 8K long and
contains 2048 entries. All indirect data extents for a given file have the
same size, which is determined when the file’s first indirect data extent
is allocated.
Version 2 inodes differ from Version 1 inodes in that they are located in
structural files to facilitate dynamic inode allocation , which is the
allocation of inodes on an as-needed basis. Instead of allocating a fixed
number of inodes into the file system, mkfs allocates a minimum number
of inodes. Additional inodes are later allocated as the file system needs
them.
The inode list is a series of inodes located in the inode list file. There is
one inode in the list for every file in a given fileset. For recovery
purposes, the inode list file is referenced by two inodes that point to the
same set of data blocks. Although the inode addresses are replicated for
recovery purposes, the inodes themselves are not.
An inode extent is an extent that contains inodes and is 8K long, by
default. Inode extents are dynamically allocated to store inodes as they
are needed.
Initial Inode List Extents The initial inode list extents contain the
inodes first allocated by mkfs_vxfs(1M) for each fileset in a file system.
During file system use, inodes are allocated as needed and are added into
the inode list files for the filesets.
Figure 2-7, “Inode Lists” shows the initial inode list extents allocated for
the primary and attribute filesets. Each of these extents contain 32
inodes and is 8K long.
The construction of the primary fileset’s inode list resembles that of the