I havent done this before and would like to know how it goes and your solution. The solution i found sounds a bit long winded but solves the problem... if you read through there are two solutions you could try.
I wish i could help you more but im no system admin but here is what iv found:
I think you many change the default server from SharePoint Central
Administration site. You can find it "Central Administration" -->
"Operations" --> "Default Database Server"
Change the name of the server to your current database server. Supply
the login password if you have SQL Server authentication. Thats all.
if that doesnt work you can try solution 2:
-On the old farm, go to central admin, application Management, Web application list. Make a note of all these applications and the URLs
associated with them
-Go back to Application management, click Site Collection List. Make a note of each site collection you have including the URL. Make sure to
check each web app by selecting it on the right hand drop down and
check the site collections in each app.
-Now you have a list of all the things you need to back up. Yay!
-use STSADM to back these up with the following command. You will run stsadm once for each entry you have noted in the steps above. I put my
backup files in a folder called “Backup” on my servers C drive so my
backup commands look like this:
Stsadm –o backup –url http://mywebapp –filename c:\backup\mywebapp.dat
-You will run this again for each webapp or site collection in your list. The command you use when backing up Site collections should
contain the full URL including the host web app, even if you have
already backed up the host webapp before. (I’m not sure why the backup
doesn’t include site collections). So in my example, if I had a site
collection at ”/sites/projects” under
http//:mywebapp then I would
need to run stsadm again like this:
Stsadm –o backup –url http://mywebapp/sites/projects –filename c:\backup\projects.dat
-After you have a backup of all your webapps/site collections, move onto building your new farm.
-On a new server, install SharePoint following whatever docs you need to make a good vanilla SharePoint install. I installed mine following
the numerous TechNet articles available. It’s not a big deal. Took
about an hour or 2. Pay attention to the persmisions sections!
-Choose to create a new farm.
-Once your new server is up and running, you will need to create all your webapps again. I don’t believe that you need to re-create your
site collections – just the webapps. That’s what I did anyway.
-Go to central Admin, application Management, Create or extend Web application.
-Create a new web application for each of your old applications (not site collections) based on the list you created at the beginning.
Again follow the M$ literature to do this properly (creating app
pools, permissions etc – it’s not hard at all)
-At this point its worth noting that I am creating my content DBs on the same DB server that my old content DBs are on. I’m calling them
sensible names though so that I can distinguish between new DBs and
Old ones and go back and delete old ones later.
-copy all your backup files from your old server to your new one. In my example I’m copying them to “C:\backups” again
-Now change your DNS so that your old web app names now point to your new sharepoint server. This is important for the restore command to
find your new server instead of the old one!
-We use stsadm again to import the data from the backup files into the new web applications by running the following command from the new
Stsadm –o restore –url http://mywebapp –filename c:\backups\mywebapp.dat
-You run this command for each of your webapps that you backed up. Once you have done all your webapps, restore your site collections by
running stsadm again. You don’t have to recreate anything first (other
than the host webapp which is hopefully already done)
Stsadm –o restore -url http://mywebapp/sites/projects –filename c:\backup\projects.dat
Hope it helps :)