HP-UX HB v13.00 Ch-14 - JFS

HP-UX Handbook – Rev 13.00 Page 46 (of 47)
Chapter 14 Journaled File System (JFS)
October 29, 2013
Features Only Available for OnlineJFS
Defragmentation of a file system
# fsadm –F vxfs –d –D –e –E <mountpoint>
-d performs a directory defragmentation
-D reports on directory fragmentation
-e performs a file extent defragmentation
-E reports on file extent fragmentation
Typically directory defragmentation is not beneficial in improving performance.
NOTE: While defragmentation can be run at anytime, it is prudent to do it when the file system
is as quiet as possible to reduce the completion time and system impact. It is not advisable to run
more than 1 defragmentation at a time.
For those systems with Base JFS , defragmentation is only available by using move (mv) or copy
(cp) .
Move is preferable as it incurs less system overhead.
Using extent attributes
Extent attributes can be manipulate using setext
#setext –e <extentsize> -r <reservationsize> -f <flag> <file>
possible flags:
align: Specify that all extents must be aligned on extent_size boundaries relative to the start of
allocation units
chgsize: Immediately incorporate the reservation into the file and update the file's on-disk inode
with size and block count information that is increased to include the reserved space. The space
added to the file is not initialized
contig: Specify that the reservation must be allocated contiguously
noextend: Specify that the file may not be extended after the preallocated space is used
noreserve:Specify that the reservation is not a persistent attribute of the file. Instead, the space