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

50 Chapter2
Disk Layout
The VxFS Version 1 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.
The inode list is a series of inodes. There is one inode in the list for every
file in the file system.
Padding It may be desirable to align data blocks to a physical
boundary. To facilitate this, the system administrator may specify that a
gap be left between the end of the inode list and the first data block.
Data Blocks The balance of the allocation unit is occupied by data
blocks. Data blocks contain the actual data stored in files and directories.