what I recommend in this case is :

1- before you start doing any thing make sure that all the important data in the production servers are backed up and safe
2-make sure that all the files with the extension ( .nsf) like names.nsf , (.id) like server.id and a file called ( notes.ini) are safe and backed up
3- follow the following procedure

Considerations for mail servers (Upgrade Action Plan)

For many organizations, e-mail is considered a mission-critical application. For this reason, special attention should be given to the evaluation of your mail infrastructure.

Road Map (Pre-installation Steps)
Check the administration request databases and see if there is any old pending request, just approve/delete it if it is necessary.
Check the log file and see if there is any error. Just try to resolve it first.
Restrict server usage using the server_restricted=1 dynamic Notes.ini parameter and drop all users from server sessions. This notes.ini parameter does not stay in effect after Domino is restarted. To maintain the setting after a Domino server restart use server_restricted=2.
Force routing of all mail still waiting for delivery, and then stop the router and SMTP tasks. To force mail that is pending to a destination server, issue the route <destination server address> Domino console command.
Delete all the debug entries if it is existing in notes.ini
Remove lan0 from notes.ini and keep only TCP
(Optional) Purge all administrative requests using adminp console command. Load command on the console “tell adminp process all” 3 to 4 times
Load the following command on the console;
 Tell router q
 Tell smtp q
 Dbcache flush
If running Domino as a service, change the startup type to manual.
Uncheck the receive design element of Domino Directory, go to names.nsf – right click and open the properties—click on Replication Settings and then Advanced, just uncheck Design Element under Receive these elements from other replicas
Stop the Domino server.
Stop Symantec and net backup services
Take the backup of ini file and id files (notes.ini, names.nsf, server.id and cert.id)
Cut and paste loadmon.nsf to somewhere. This database will create automatically after upgrade the server
Upgraded Symantec AV from version 4.5 to version 7.5 on both servers (if required).

Lotus Domino v8 Installation
Run Domino 8.0.2 setup on the server

Road Map (Post-installation Steps)
Change the startup type to Automatic.
Run all the services including Symantec and backup
Run the following command if lotus domino is not appearing as a service
ntsvinst -c -t”Lotus Domino Server (lotusdominodata)” -ic:\notes\alice\data\notes.ini
Add the parameter (Create_R8_Databases=1) in notes.ini
Open the command prompt and run the following commands,

 Ndesign –f names.nsf ————– (to update the design of Domino Directory)
 Nupdall –R names.nsf ————– (to update the views of Domino Directory)
 Nupdall names.nsf –t ($Users) –R (to update the users views)
 Nupdall names.nsf –t ($ServerAccess) –R (to update server views)
 Ncompact –c names.nsf ———– (to convert the ODS Version)
 Ncompact –c admin4.nsf ———- (to convert the ODS Version)
 Ncompact –c event4.nsf ———– (to convert the ODS Version)
 Ncompact –c log.nsf —————- (to convert the ODS Version)
 Ncompact –c ddm.nsf ————– (to convert the ODS Version)

Edit the notes.ini parameter from Server_Restricted=2 to Server_Restricted=0
Start Domino Server
Update the view and indexes using updall console command (load updall -R)
Check the ODS Version of Admin4.nsf, Names.nsf, Log.nsf, Events4.nsf and DDM.nsf if these are converted from 43 to 48.
Check the Server Document if the Domino version is change from old to new.
Replicate names.nsf and Admin.nsf from the administration server to the upgraded server (in BSF environment it will be from CENNOT01 to the upgraded server)
In the night at the time to leave the office just run the compact command (load compact -c) on all the databases to convert the ODS Version.