linux- after unmounting filesystem mounts back again

view story

http://stackoverflow.com – I am unmounting a couple of file system in linux and replacing them with different filesytem but after unmounting, those file system comes back again after some time. Is there any other config file I am missing ? Our build scripts depend on particular filesytem and these new boxes came with a different one hence trying to change the filesystem. I did "umount ", did "mount | grep " twice, the second time filesytem is seen again in the output. (/etc/fstab does not have an entry for this) (HowTos)