Veritas File System 5.1 SP1 Administrator"s Guide (5900-1499, April 2011)

The vxtunefs command allows the administrator to set or view the default indirect
data extent size of a file system.
See the vxtunefs(1M) manual page.
Fast file system recovery
Most file systems rely on full structural verification by the fsck utility as the only
means to recover from a system failure. For large disk configurations, this involves
a time-consuming process of checking the entire structure, verifying that the file
system is intact, and correcting any inconsistencies. VxFS provides fast recovery
with the VxFS intent log and VxFS intent log resizing features.
VxFS intent log
VxFS reduces system failure recovery times by tracking file system activity in the
VxFS intent log. This feature records pending changes to the file system structure
in a circular intent log. The intent log recovery feature is not readily apparent to
users or a system administrator except during a system failure. During system
failure recovery, the VxFS fsck utility performs an intent log replay, which scans
the intent log and nullifies or completes file system operations that were active
when the system failed. The file system can then be mounted without completing
a full structural check of the entire file system. Replaying the intent log may not
completely recover the damaged file system structure if there was a disk hardware
failure; hardware problems may require a complete system check using the fsck
utility provided with VxFS.
The mount command automatically runs the VxFS fsck command to perform an
intent log replay if the mount command detects a dirty log in the file system. This
functionality is only supported on a file system mounted on a Veritas Volume
Manager (VxVM) volume, and is supported on cluster file systems.
See “The log option and data integrity” on page 23.
VxFS intent log resizing
The VxFS intent log is allocated when the file system is first created. The size of
the intent log is based on the size of the file system—the larger the file system,
the larger the intent log. The maximum default intent log size for disk layout
Versions 5 and 6 is 16 megabytes. The maximum default intent log size for disk
layout Version 7 and 8 is 64 megabytes.
With the Version 6, 7, and 8 disk layouts, you can dynamically increase or decrease
the intent log size using the logsize option of the fsadm command. Increasing
the size of the intent log can improve system performance because it reduces the
21Introducing Veritas File System
Veritas File System features