Incremental backup - RTO and RPO considerations
11 January 2017 07:00 PM
This article discusses the effects of the incremental backup implementation on Recovery Point Objectives (RPO) and Recovery Time Objectives (RTO).
With MarkLogic 8 you can have multiple daily incremental backups with minimal impact on database performance.
Incrementals complete more quickly than full backups reducing the backup window. A smaller backup window enables more frequent backups, reducing the RPO of the database in case of disaster.
However, RTO can be longer when using incremental backups compared to just full backups, because multiple backups must be restored to recover.
There are two modes of operation when using incremental backups:
Incremental since last full. Here, each incremental has to store all the data that has changed since the last full backup. Since a restore only has to go through a single incremental data set, the server is able to perform a faster restore. However, each incremental data set is bigger and takes longer to complete than the previous data set because it stores all changes that were included in the previous incremental.
Please note when doing “Incremental since last full”:-
- Create a new incremental backup directory for each incremental backup
- Call database-incremental-backup with incremental-dir set to the new incremental backup directory
Incremental since last incremental. In this case, a new incremental stores only changes since the last incremental, also known as delta backups. By storing only the changes since the last incremental, the incremental backup sets are smaller in size and are faster to complete. However, a restore operation would have to go through multiple data sets.
Please note when doing “Incremental since last incremental”:-
- Create an incremental backup directory ONCE
- Call database-incremental-backup with the same incremental backup directory.
See also the documentation on Incremental Backup.