How to restore system databases on lower build

knowledge sharing : Restoring System databases on different build

Issue :

Datafiles and log files are lost on Uat server  due to OS issue
------> Sql server is down
------> All data and log files lost including system database
------> Only backups are available

Action required :

1. Re-install SQL server 2000
2. Restore all databases including system datbases

Problem:

Dba installed SQL 2000 sp4 8.00.2196 whereas previous version was 8.00.2189 (backup belongs to build 8.00.2189 )
which results error in restoring system databases (user databases restored without issue)

Resolution:

1. Restore master database as user databases with definetely modified names(may be master_user)
2. Stop sql services
3. Copy original master db data and log file in different folder
4. Replace master database data and log file @ default folder with new data and log files of Restored master_user(user) database.
5. Check name of master databases data and log file, it should be same as stored in sqlserver
6  Start sql server in single user mode
7. check in errorlog if system databases is recovered
8. stop and start sqlserver in normal mode
9. Repeat same step for model and master database as well


refrence link :    http://support.microsoft.com/kb/264474