Recover a SQL Server From Backups Only

Posted: August 7, 2013 in Backups, DBA, Disaster Recovery

The Problem

The server was on a VM and the system drive was backed up. We had separate drives for SQL Data, SQL Logs and SQL Backups. Only the backups went to tape.
As part of the decommissioning of a server we lost all the drives on our production box.
They were replaced and the system disk restored. The SQL Backups were also restored. The data and log drives were empty.

The Solution

The restore of the system drive gave us the SQL binaries but we lacked the system databases. In our support database I had a record of where the data and log files were stored so I could recreate the directory structures. I also used the SQL Config manager to find out where the error logs went and created those directories too.
SQL wouldn’t start, however, as there was no master db. To get it going I found another instance of SQL which was at the same product level. I copied the master mdf and ldf into the appropriate drives (I had to stop this SQL instance to get these files as they can’t be copied while SQL is running). I was now able to get SQL to start for a second. It was filing now due to a lack of Tempdb.
At first I was a bit confused as Tempdb is created when SQL server starts. Then I remembered that it was created from model. I went back to that other SQL install and took a copy of model mdf and ldf.
I was now able to Start SQL up and attempt to do a restore of the local master db.
At this point I encountered another issue. To restore master you need SQL to be running in single user mode. That’s fine but there was an app which was connecting to this box every half-second and it kept stealing that single session.
To stop the app I used IPSec (http://searchwindowsserver.techtarget.com/feature/Use-IPSec-to-manage-connections) to block the ip address the app was using – I got this from the SQL error logs. Thinking about it now I might have been able to turn of TCIP and used shared memory.
With the app blocked I was able to restore maters and then MSDB. I didn’t do Model as the copy I had borrowed was from an identically set-up SQL. You may want to restore model to be on the safe side.
At this point I could start SQL up normally and from SSMS I did a restore of all the user databases.

Lessons

We are now creating an archive of Master and model mdf and ldf files. We can then use these without stopping another SQL instance.
You could also copy master and model files into the backup directory whenever you do a new build, apply a service pack or create a hot fix (ie whenever the version number changes). You could then pull these from the backup directory.

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