WHat is the difference between Veritas filesystem and veritas volume manager?

Regards

I had trouble with this in the beginning also.

Volume Manager has to do with managing the disks, raid, striping, plexes, etc....

Veritas Filesystem is just that. Anything that you need to do to manage the data on the disks. Such as mkfs, mount, online resizing and defragmenting. It also gives you control over I/O, caching, and allocation.

Remember:
VM is managing the disks.

Veritas Filesystem is managing the data on the disks.

The Veritas filesystem is the filesystem used for specific partitions. It is controlled by the Veritas Volume Manager which is a gui software interface to create the different volumes being used (by Oracle, Sybase, and other applications). Normally UNIX OS does not need to be placed under Veritas but could (although failures in drives then creates more of a headache for the OS recovery.)