Performing an External Backup

The database server must be online or in quiescent mode during an external backup.

To perform an external backup without disk mirroring

To obtain an external backup, block the database server. The system takes a checkpoint and suspends all update transactions. Users can access the database server in read-only mode.
Use the following command:
```
onmode -c block
```
To back up the storage spaces and administrative files, use a copy command, such as cp, dd, or tar on UNIX or copy on Windows, or a file-backup program. You must back up all chunks in the storage spaces.
To allow normal operations to resume, unblock the database server.
Use the following command:
```
onmode -c unblock
```
Back up all the logical logs including the current log so that checkpoint information is available for the external restore.
Warning:

Because external backup is not done through ontape, you must ensure that you have a backup of the current logical log from the time when you execute the onutil EBR BLOCK or onmode -c block command. Without a backup of this logical-log file, the external backup is not restorable.
After you perform an external backup, back up the current log.
Use the following command to back up the current log:
```
ontape -a
```

If you lose a disk or the whole system, you are now ready to perform an external restore.