Restoring Db2 from an online backup

This process restores a database that was backed up by using the db2 backup command. The restored database starts back in the same state that it was in when the online backup was made.

Before you begin

You must have an existing Db2 backup that is accessible on the IBM Software Hub system.
You must identify the Db2 catalog node and data nodes and have an SSH connection open to each node.

Note: The following commands use the environment variable that contains the default database name: ${DBNAME}. If you have multiple databases, update the commands or variable value.

About this task

For a Db2 deployment, the db2 restore command can be started only from the catalog node but each available multiple logical node (MLN) participates in the restore operation.

Restriction: A full database restore operation can be run only in offline mode.

Procedure

Switch to the database instance owner from a bash shell on each of the nodes specified in the db2nodes.cfg file. Confirm that the directory that contains the database backup exists and is mounted. For example:
```
su - db2inst1
cd /backup_dir/backup_nnn
```
Where backup_dir is the directory that you create to hold backup images and nnn is an incremental value that was used to put each backup in a separate subdirectory. The backups can be in any directory on the cluster that is shared by the container nodes and has sufficient space to hold the backups. If you restore a backup from a different directory location, alter these commands as necessary.

Disable the built-in HA temporarily:

sudo wvcli system disable -m "Disable HA before Db2 maintenance"

Connect to the database:
```
db2 connect to ${DBNAME}
```
Find all the applications that are connected to Db2 on the catalog node.
```
db2 list applications
```
You can either stop all the connections by closing the applications, or you can enter the following command to disconnect all connections:
```
db2 force application all
```
Issue the terminate database command:
```
db2 terminate
```
Stop the database:
```
db2stop force
```
Ensure that the command completes on all nodes.
Ensure that all Db2 interprocess communications are cleaned for the instance:
```
ipclean -a
```
Turn off all communications to the database by setting the value of the DB2COMM variable to null:
```
db2set -null DB2COMM
```
Restart the database in restricted access mode:
```
db2start admin mode restricted access
```
Run the restore operation:
1. On the catalog node, run the following command:
```
db2 RESTORE DATABASE ${DBNAME} FROM backup_dir TAKEN AT backup_image_timestamp INTO ${DBNAME} REPLACE EXISTING WITHOUT PROMPTING
```
  Where backup_dir is the full path to the directory where your backup images are located, and backup_image_timestamp is the associated timestamp on those backup image files.
2. After the commands are complete, roll forward the database by running the following command on the catalog node:
```
db2 rollforward db ${DBNAME} to end of backup on all dbpartitionnums and stop
```
Stop the database:
```
db2stop force
```
Ensure that the command completes on all nodes.
Ensure that all Db2 interprocess communications are cleaned for the instance:
```
ipclean -a
```
Reinitialize the Db2 communication manager to accept database connections:
```
db2set DB2COMM=TCPIP,SSL
```
Restart the database for normal operation:
```
db2start
```
The online database restore operation is complete.
Activate the database:
```
db2 activate db ${DBNAME}
```
Re-enable the Wolverine high availability monitoring process:
```
wvcli system enable -m "Enable HA after Db2 maintenance"
```
Connect to the database:
```
db2 connect to ${DBNAME}
```

What to do next

For more information about advanced command options, see the RESTORE DATABASE command