Veritas File System 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

VxFS Performance: Creating, Mounting, and Tuning File Systems
I/O Tuning
Chapter 246
default_indir_
size
On VxFS, files can have up to ten direct extents of variable size
stored in the inode. Once these extents are used up, the file must use
indirect extents which are a fixed size that is set when the file first
uses indirect extents. These indirect extents are 8K by default. The
file system does not use larger indirect extents because it must fail a
write and return ENOSPC if there are no extents available that are the
indirect extent size. For file systems with many large files, the 8K
indirect extent size is too small. The files that get into indirect extents
use many smaller extents instead of a few larger ones. By using this
parameter, the default indirect extent size can be increased so large
that files in indirects use fewer larger extents. The tunable
default_indir_size should be used carefully. If it is set too
large, then writes will fail when they are unable to allocate extents of
the indirect extent size to a file. In general, the fewer and the larger
the files on a file system, the larger the default_indir_size can
be set. This parameter should generally be set to some multiple of the
read_pref_io parameter. default_indir_size is not
applicable on Version 4 and Version 5 disk layouts.
fcl_keeptime 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.