Backup
- Backup is the process of making a second copy of data that can be restored to use at any time if the primary copy becomes lost or unusable.
- Backups usually comprise a point-in-time copy of primary data taken on a repeated cycle – daily, monthly or weekly.
A backup may be required in the following scenarios:
- Logical corruption
- User error
- Hardware failure
- Hardware loss
Snapshot
Snapshot is a point-in-time copy of data created from a set of markers pointing to stored data and is effectively a backup. Snapshots provide a variety of approaches that can supplement backup and provide rapidly accessible copies to which is it possible to roll back.
Failover
Failover is the constant capability to automatically and seamlessly switch to a highly reliable backup. This can be operated in a redundant manner or in a standby operational mode upon the failure of a primary server, application, system or another primary system component.
There are two types of options to overcome failover
- High Availability
- Fault Tolerance
High Availability - If the Host / Server failed the running virtual machines are moved to other hosts with down, we need power up manually
Fault Tolerance - If the Host / Server failed virtual machines are moved to other hosts without downtime, no need power up manually
