All the active logs, disk buffers, and related data are stored in volatile storage such as RAM. Moreover, it stores all the transactions that are currently being executed. What happens if such a volatile storage system suddenly crashes? Obviously, it would take away all of the database's logs and active copies. This makes recovery nearly impossible, as all that is needed to recover the data is lost.
In the case of loss of volatile storage, the following techniques could be used
A catastrophic failure is one where it corrupts a stable, secondary storage device. All the valuable information that is stored inside the storage device is lost. To recover data from such a catastrophic failure, we have two separate methods.
Grown-up databases are too bulky to be backed up frequently. In such cases, we have techniques where we can restore a database just by looking at its logs. All we need to do here, then, is take a backup of all the logs at frequent time intervals. The database can be backed up once a week, and the logs being very small can be backed up every day or as frequently as possible.
In the case that the primary location where the database is located is destroyed, remote backup provides a sense of security. Remote backup may be offline or online or in real-time. In case it is offline, it is maintained manually.
To database administrators and investors, online backup systems are more real-time and lifesavers. An online backup system is a process where two distant places simultaneously back up any bit of real-time data. One of them is directly linked to the system and the other is held as a backup in a remote place.
The backup mechanism senses the failure as soon as the primary database storage fails and switches the user system to remote storage. This is sometimes so instant that a failure can't even be came to realize by the users.