Since you mentioned vserver, this is CluserMode, correct?
Root volumes are not always read-only.
You don't mention how you see this volume as read-only; but if it is via a CIFS share, the following may be helpful:
If you have a CIFS share to a volume with load-sharing mirrors, you will be connected to the load-sharing mirrors, which are read-only. If you want to connect to the actual root volume you need to create a CIFS share with the path set to "./admin", this share will put you on the actual root volume, and not one of the load-sharing copies. Take proper precautions with who can access this share, this is to the root of your filesystem.
If you are not accessing this via CIFS, or you do not have load-sharing mirrors in place for this root volume, something else may be going on (e.g. the share is read-only, if NFS, export is ro, etc).