may you please guide me on step by step on how to upgrade on vmware. do i follow the same guide as installation on virtual appliance bundle. or must i import the file (nmis-8.5.12G-VM-CentOS-6.8-64bit) to host?
you should upgrade to the newest NMIS version, 8.6.0G, not 8.5.12G.
the upgrade will work just like an opmantek application upgrade on a non-virtual server would work: download the self-extracting installer file from our website, transfer it to the system in question (sftp, scp etc.), start the installer and follow the prompts (as described on the NMIS 8 Installation Guide and Upgrading NMIS to 8.6.0G pages).
the zip file you mention (nmis...VM...) /is/ the whole virtual appliance; it's not relevant for upgrading an existing installation.
i downloaded the upgrade file which is nmis8.6.0.run file do i need to change file extension. i am using winscp to connect to a remote server on vm ware.
no need to change the file extension. the nmis.run file needs to be transferred to the system you're upgrading, then you need to connect interactively to that system and start the installer. see https://community.opmantek.com/display/NMIS/NMIS+8+Installation+Guide#NMIS8InstallationGuide-StartingtheInstaller for details.
i will do that and revert. thanks for your help.