Using a split mirror as a backup image in a Db2 pureScale environment (Linux)

Use the following procedure to create a split mirror of a database in a different location on the same system for use as a backup image in a Db2 pureScale environment. This procedure can be used instead of performing backup database operations on the database. This procedure is only applicable in Linux systems.

About this task

Important: To run the db2cm utility as the root user, ensure the DB2INSTANCE environment variable is set to the instance owner.

Procedure

To use a split mirror as a backup image:

Connect to the primary database using the following command:
```
db2 connect to <db_name>
```
Configure the General Parallel File System (GPFS) on the secondary cluster by extracting and importing the settings from the primary cluster. On the primary cluster, run the following GPFS command:
```
mmfsctl filesystem syncFSconfig -n remotenodefile
```
where remotenodefile is the list of hosts in the secondary cluster.
Suspend the I/O write operations for the primary database using the following command:
```
db2 set write suspend for database
```
Note: While the database is in suspended state, you should not be running other utilities or tools. You should only be making a copy of the database. You can optionally flush all buffer pools before issuing SET WRITE SUSPEND to minimize the recovery window. This can be achieved using the FLUSH BUFFERPOOLS ALL statement.
Determine which file systems must be suspended and copied using the following command:
```
db2cm -cfs -list -filesystem
```
Suspend each GPFS file system that contains container data or log data using the following command:
```
/usr/lpp/mmfs/bin/mmfsctl filesystem suspend-write
```
where filesystem represents a file system that contains data or log data.
Note: While the GPFS file systems are suspended, write operations are blocked. You should only be performing the split mirror operations during this period to minimize the amount of time that operations are blocked.
Create one or multiple split mirrors from the primary database using appropriate operating system-level and storage-level commands.
Note:
- Ensure that you copy the entire database directory including the volume directory. You must also copy the log directory and any container directories that exist outside the database directory. If you are using multiple storage groups, you must copy all paths, including files and subdirectories of those paths. To gather this information, refer to the DBPATHS administrative view, which shows all the files and directories of the database that need to be split.
- If you specified the EXCLUDE LOGS with the SET WRITE command, do not include the log files in the copy.
Resume the GPFS file systems that were suspended using the following command for each suspended file system:
```
/usr/lpp/mmfs/bin/mmfsctl filesystem resume
```
where filesystem represents a suspended file system that contains data or log data.
Resume the I/O write operations for the primary database using the following command:
```
db2 set write resume for database
```

Assuming that a situation requires you to restore the database using the split mirror as the backup image, perform the following steps:

Stop the primary database instance using the following command:
```
db2stop
```
Stop the cluster manager on each host in the cluster using the following command:
```
db2cm -cm -stop -host host -force
```
Note: The last host which you shut down must be the host from which you are issuing this command.
Stop the GPFS cluster on the primary database instance using the following command:
```
db2cm -cfs -stop -all
```
Copy the split-off data off the primary database using appropriate operating system-level commands.
Important: Do not copy the split-off log files, because the original logs are needed for rollforward recovery.
Start the GPFS cluster on the primary database instance using the following command:
```
db2cm -cfs -start -all
```
Start the cluster manager using the following command:
```
db2cm -cm -start -domain
```
Start the database instance using the following command:
```
db2start
```
Initialize the primary database using the following command:
```
db2inidb database_alias as mirror
```
Rollforward the primary database to the end of the logs, or to a point-in-time, and stop.