I'm confused because as I know, CentOS doesn't support ReiserFS.
But my previous CentOS VPS is running on ReiserFS.
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/vzfs reiserfs 314572800 10694756 303878044 4% /
none tmpfs 262144 4 262140 1% /dev
In system admin view, What make it possible to install CentOS with ReiserFS in VPS?
This looks like it's probably a case of your VPS swapped in a new kernel compiled with ReiserFS support, instead of using the kernel that came with CentOS which is not built with ReiserFS support.