SAP HANA backup and recovery Keeps the Data Safe in Case of Database Failure
An In-memory database is SAP HANA where all the data are saved in RAM. Since RAM is a volatile memory all data can get lost if the power gets down. But in case of SAP HANA a disc memory is also present which acts as backup. At regular savepoints all data is saved automatically from memory to disk in the course of normal operation. Like any disk-based database, SAP HANA can be restarted after a power gets down and by replaying the redo log entries since the last savepoint it returns to its last consistent state.
Reasons for the requirement of SAP HANA backups:
- It helps in safeguarding the data against the disk failures
- It makes it likely to reset the database to a previous point in time.
- It helps in maintaining atomicity, consistency, isolation and durability (ACID). Durability is a necessity that is not met by storing data in main memory only. Since main memory is volatile storage it misplaces its content when it is out of power. Thus, it resides on non-volatile storage, such as SSD, hard drives, or Flash devices to make data persistent.
Thus, Backup and Recovery is the method of copying and storing data for the definite purpose of reestablishing. Files backup can defend against inadvertent loss of user data, database exploitation, hardware letdowns, and even natural calamities.
The most important parameters of a disaster recovery or data protection plan are:
Recovery Point Objective (RPO)
Recovery Time Objective (RTO)
RTO (Recovery Time Objective) has a comprehensive purpose as it sets the limits for the entire business continuity management, while RPO (Recovery Point Objective) is concentrated only on the problem of backup frequency. Both of them are vital for business impact analysis and for business continuity management. Without understanding them properly, one would not be able to find out the best way to recover from a disaster.
Function of Data backups/snapshots and log backups:
- Data backups save all the existing data and save changed data afterwards while log backups save the redo log entries.
- They are executed manually while log backups are carried out automatically.
- Data backups can be full and Delta data backup. The Delta data backup can be of two types incremental and differential.
- Snapshots are a substitute to full data backups while log backups do not have such options.
Thus, it can be said that SAP HANA uses persistent storage to provide a backup in case of power or a database failure.