VxFS filesystems can be defragmented using the fsadm command. However,
the online reorganization and online resize features of fsadm are
enabled only with the HP OnLineJFS optional product.
Here are the relevant options:
 -D Report on directory fragmentation. If specified in
 conjunction with the -d option, the fragmentation
 report is produced both before and after the
 directory reorganization.
 -d Reorganize directories. Directory entries are
 reordered to place subdirectory entries first, then
 all other entries in decreasing order of time of last
 access. The directory is also compacted to remove
 free space.
 -E Report on extent fragmentation. If specified in
 conjunction with the -e option, the fragmentation
 report is produced both before and after the extent
 reorganization.
 -e Reorganize extents. Minimize file system
 fragmentation. Files are reorganized to have the
 minimum number of extents.
An example:
 # fsadm -dDeE /var
See fsadm_vxfs(1M) for further details.
No commands are available for defragmenting HFS filesystems.