This article introduces what are the most important factors during making the backup strategies.

During making the backup strategies, the main factors to consider are how much data could be lost and how much downtime the business could tolerate which is measured by RTO and RPO. Another factor to consider is the retention period, which defines the duration of the backup data required by the business.  Some data should be stored for several years while others only need to be retained for a few days. For example, the retaining time of archiving backup data is longer than the recovery operation data.

According to the retaining time and data availability, the type of the backup media is also a very important factor. The backup granularity must be taken into account when building the infrastructure. When making backup strategy a best backup time should be determined, so that the interruption to the productive operations could be reduced to the minimum. Similarly, the location and time of the recovery operation should also be considered according to the file characters and data compression which could affect the backup.

Since the file location, size and number could affect the backup process, they should also be considered. For the data to backup, location is a very important consideration.  Many organizations have plenty of heterogeneous platforms to support complex solutions, such as data warehouse environment using the backup data from many sources. The backup process must illustrate these sources by interactions and content integrity way, and the process must be completed with the cooperation of all the heterogeneous platform storing the data.

File size also affects the backup process. Backup large files (such as 10 1MB files) may use less resource than the same amount of data but composed of plenty of small files (such as 10000 1KB files). When file systems comprise plenty of small files, backup and recovery process will take more time.

Similar to the file size, the number of backup files can also affect the backup process. For example, in incremental backup, a file system with 1000000 files and 10% daily changing rate will have to create 100000 entries in the backup directory.  Backup directory contains a content table of the backup data and information about the backup session. Such a large number of entries in the file system will affect the performance of the backup and recovery process due to that searching for a file system takes too long.

Backup performance is also dependent on the backup media used.  Long time start and stop operation in a tape-based system will affect backup performance, especially in a large number of small files backup.

Since compression could save the media space, it is widely used in the backup system. Many backup devices (such as tape drives) have built-in hardware-based data compression support. In order to utilize compression effectively, it is very important to understand the characteristics of the data. Some data (such as application data) cannot be well compressed, while text data is suitable for compression, other data (such as JPEG and ZIP files) are compressed already.

Author:Jiawen