i've an old 5.x version of vm, and i don't want to download the new version.
can any body advise how i can upgrade it to the latest version, using the old installation?
If you are just using the out-of-the-box CDH installation, you should be able to upgrade normally. It can be as simple as 'sudo yum update', but do consult the documentation for any other gotchas. If you have used one of the provided script to migrate to CM, you should also be able to upgrade CM and CDH the normal way (update CM packages, then use CDH to update the CDH version on the 'cluster'). Do note, however, that if your VM currently has the scripts to migrate to CM and use parcels, they may not work after you upgrade or may work but will use the original CDH version the VM was downloaded with. The eclipse environment and some other files may also cease working if versions change.
As Dima suggested, it is likely going to be easier to download the new VM, unless you specifically need a maintenance release for which a VM was not released (e.g. 5.5.1)
by the way does upgrading cloudera manager means that we've upgraded the whole instance? OR each every application or service need to be upgraded manually
well i've not used the earlier downloaded version, therefore also want to see for having more knowledge that how can i upgrade it later on?