Difference between UFS and VxFS :-

The following differences summarize the tests done by veritas.

1. VxFS has faster recovery from unusual events like disk corruption.
2. VxFS is 8-20 % faster on database performance than UFS.
3. fsck on vxfs are 6 times faster than UFS with logging.
4. Performs better during multiprocess operations. 300% more than UFS during concurrent loads.
5. Emhanced Mount options like blkclear, closesync.
6. Administration is online, reszing, defragmentation e.t.c.

The most prominent difference is the extent based allocation thats default in vxfs as opposed to the block based allocation of UFS.

An extent is cluster of contigous blocks. Writes to extents is faster during multiple operations since more number of disks can respond. Also useful when files are large and when the fs is subjected to sequential i/o.