VERITAS File System 4.1 Administrator's Guide

File Change Log
File Change Log Administrative Interface
Chapter 8 133
File Change Log Administrative Interface
The FCL can be set up and tuned through the VxFS administrative commands fcladm and
vxtunefs. The FCL tunable parameters are:
fcl_keeptime Specifies the duration in seconds that FCL records stay in the FCL file
before they can be purged. The first records to be purged are the oldest ones,
which are located at the beginning of the file. Additionally, records at the
beginning of the file can be purged if allocation to the FCL file exceeds
fcl_maxalloc bytes. The default value is 0. Note that fcl_keeptime takes
precedence over fcl_maxalloc. No hole is punched if the FCL file exceeds
fcl_maxalloc bytes but the life of the oldest record has not reached
fcl_keeptime seconds.
fcl_maxalloc Specifies the maximum number of spaces in bytes to be allocated to the FCL
file. When the space allocated exceeds fcl_maxalloc, a hole is punched at the
beginning of the file. As a result, records are purged and the first valid offset
(fc_foff) is updated. The minimum value of fcl_maxalloc is 4MB. The default
value is fs_size/33.
fcl_winterval Specifies the time in seconds that must elapse before the FCL records an
overwrite, extending write, or a truncate. This helps to reduce the number of
repetitive records in the FCL. fcl_winterval time-out is per inode. If an inode
happens to go out of cache and returns, its write interval is reset. As a
result, there could be more than one write record for that file in the same
write interval. The default value is 3600 seconds.
Either or both fcl_maxalloc/fcl_keeptime must be set to activate the FCL. The following
are examples of using the FCL administration command.
To activate the FCL for a mounted file system, enter:
# fcladm on mount_point
To deactivate the FCL for a mounted file system, enter:
# fcladm off mount_point
To remove the FCL file for a mounted file system (the FCL must be OFF before it can be
removed), enter:
# fcladm rm mount_point
To obtain the current FCL state for a mounted file system, enter:
# fcladm state mount_point