Veritas™ File System 5.0.1 Administrator's Guide

Table 2-1
Tunable VxFS I/O parameters (continued)
DescriptionParameter
Specifies the minimum amount of time, in seconds, that
the VxFS File Change Log (FCL) keeps records in the log.
When the oldest 8K block of FCL records have been kept
longer than the value of fcl_keeptime, they are purged
from the FCL and the extents nearest to the beginning of
the FCL file are freed. This process is referred to as
"punching a hole." Holes are punched in the FCL file in
8K chunks.
If the fcl_maxalloc parameter is set, records are purged
from the FCL if the amount of space allocated to the FCL
exceeds fcl_maxalloc, even if the elapsed time the
records have been in the log is less than the value of
fcl_keeptime. If the file system runs out of space before
fcl_keeptime is reached, the FCL is deactivated.
Either or both of the fcl_keeptime or fcl_maxalloc
parameters must be set before the File Change Log can be
activated. fcl_keeptime does not apply to disk layout
Versions 1 through 5.
fcl_keeptime
Specifies the maximum amount of space that can be
allocated to the VxFS File Change Log (FCL). The FCL file
is a sparse file that grows as changes occur in the file
system. When the space allocated to the FCL file reaches
the fcl_maxalloc value, the oldest FCL records are
purged from the FCL and the extents nearest to the
beginning of the FCL file are freed. This process is referred
to as “punching a hole.” Holes are punched in the FCL file
in 8K chunks. If the file system runs out of space before
fcl_maxalloc is reached, the FCL is deactivated.
The minimum value of fcl_maxalloc is 4 MB. The
default value is fs_size/33.
Either or both of the fcl_maxalloc or fcl_keeptime
parameters must be set before the File Change Log can be
activated. fcl_maxalloc does not apply to disk lay out
Versions 1 through 5.
fcl_maxalloc
VxFS performance: creating, mounting, and tuning file systems
Tuning I/O
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