Check DR guide (you would use nsdr to restore config).

However, when planning this there is even easier step (depending on size) which is to stop NW and make copy or res, mm and index folder.  Once done with reinstall, install NW, stop NW, copy back data and start services again.  You must make sure to use exactly same OS settings for the name of the box.

Because you say 'reinstall' I am not sure what you really want to do.

If you just want to run a local NW upgrade then NW technically does an uninstall followed by a reinstall. He leaves the databases behind so that you have the exact same configuration as before.

If you do a manual uninstall, the same happens. The databases will be left behind.

So when you reinstall, just make sure that you chose the exact same pathname.

where i can copy it( folder location ) ??? ????  and what "res" and "mm" and "index" ????
and after copy it past it back where ???

i want to upgrade form 9.0.0.* to 9.0.1 thats all
with same license same configuration how can i do it ??
i think just install new software and don't uninstall old one and merge database that's it ????

but during install he ask about password ( if i forget old password and entered new one does it make change ????)

If you are updating only NW, then just run new installer and it will take care of the rest.  9.0.0.x to 9.0.1.x is just SP post patching so no new update enabler license is needed. 

Password you should remember as it is required for auth mechanisms.  If you forgot those, not sure myself how to fix it, but you can ask support to give you a hand with that one.

You will find the NW database direcories in your installation path (look at a service - properties), in

  ..\nsr\index\ ,   ..\nsr\mm\ ,   ..\nsr\res\

'index' contains your file index databases (1 subdir per client)

'mm' contains your media index db.

'res' contains your configuration (plus some process databases).

i upgrade networker and when i connected i faced this error after login to console and try to open networker server

Unable to connect to server: Unable to set user privileges based on user token for SYSTEM Unable to validate the security token

how can i make old usernames can access networker  ???

i read this "

This error message appears when you try to connect to a NetWorker server that is not the host that is used to authenticate the NMC users.

To resolve this issue, establish a trust between the NMC server and the NetWorker server, and then configure user access. "Configuring the NMC server to manage additional NetWorker servers" provides more information. "

but how can i do this

???

**update **

1-

i fix it using
https://www.emc.com/collateral/TechnicalDocument/docu61086.pdf

page 165

nsrauthtrust -H Authentication_service_host -P Authentication_service_port_number

2- during upgrade i entered another keystore password  ( i think i didn't make any change ) i don't know what will it effect
i do this all in lab ... not real environment