About defragmentation

Free resources are initially aligned and allocated to files in an order that provides optimal performance. On an active file system, the original order of free resources is lost over time as files are created, removed, and resized. The file system is spread farther along the disk, leaving unused gaps or fragments between areas that are in use. This process is known as fragmentation and leads to degraded performance because the file system has fewer options when assigning a free extent to a file (a group of contiguous data blocks).

VxFS provides the online administration utility fsadm to resolve the problem of fragmentation.

The fsadm utility defragments a mounted file system by performing the following actions:

This utility can run on demand and should be scheduled regularly as a cron job.

See the fsadm_vxfs(1M) manual page.