You can copy the active plane to the inactive plane.
You should really have some idea of what you are doing, but if you want to you can do something like this:
On active:
Take a backup to rsd before starting anything else!
enable activity freeze [panel enable and freeze on]
part [partition the active plane - answer yes to any questions]
if that fails, you can try 'file dis red' and try again.
When you enter 'wh' there should be a '*' next to plane identifer to indicate partitioned. eg. A Act * [or similar]
On the inactive you need to format the disk:
** Double check you are on the inactive plane! If you get this wrong you format your active plane... Use the 'wh' command.
file dis red [do not miss this step out - otherwise the format can time-out]
vol for disk sysuser load $8000 redun $10000 scr [can take up to 40 mins]
Once formatted, log back into the active and enter:
vol set sysuser read only [vol info to check]
Then back to the inactive and enter:
vol restore sysuser from other [you should see the hard drive lights flash - probably 30 mins]
Once that is completed go back to the active and enter:
vol set sysuser read write ['vol info' to check - system won't join if not completed]
Then load the inactive - press panel enable and load a or b or use the load command - should come back with correct version of software with options and database.
Once inactive loaded, see if it is partitioned or not - 'wh' command
If inactive is showing partitioned issue 'join' command
If not partitioned, I would 'part' it then wait 5 mins then 'join' it [probably unnecessary but will do no harm].
Then on the active issue 'join' command. Inactive will reload automatically and they will sync up hopefully.
You can use 'file stat red' to see how you are doing.
Good luck.