What is source-side compression and deduplication, and how do they affect backup speed?

The process of transferring backups over the network often hits the bandwidth limitations of communication channels, especially if company offices are geographically dispersed. To solve this problem, data reduction algorithms are applied directly on the source computer or server before the data is sent to the storage repository.

Data compression analyzes files for repeating byte sequences and packs them more compactly. There are various compression algorithms that offer a balance between processing speed and the degree of size reduction. Strong compression saves disk space and traffic, but heavily loads the central processor of the machine performing the backup.

Source-side deduplication works at the data block level rather than the file level. The system breaks the information stream into small blocks and calculates a unique mathematical hash for each. If such a block has already been sent earlier in previous backup sessions, it is not transmitted again, and a simple reference is created pointing to it.

Using these technologies significantly reduces the load on the network infrastructure and allows reducing backup creation time during peak hours. However, administrators must take into account that weak computing hardware at the source can significantly slow down the process due to intensive mathematical calculations required for deduplication.