Estimating Performance

Bacula Enterprise Only

This solution is only available for Bacula Enterprise. For subscription inquiries, please reach out to sales@baculasystems.com.

The tables below include timing in seconds for a series of backups with the Accurate = yes directive in the Job resource and EnableSnapshot = yes directive in the Fileset resource. The client ZFS file system in the examples below contains 12.5 million small files.

Ubuntu 22 with 32MB RAM

Total	Accurate Setup	ZDB Scan	Scan	Backup Type
1177	0	0	1103	Full, BSnapDiff disabled
633	168	0	465	Incremental, BSnapDiff disabled
915	165	172	578	Incremental, BSnapDiff enabled
218	165	0	53	Incremental, BSnapDiff enabled

FreeBSD 32MB RAM

Total	Accurate Setup	ZDB Scan	Scan	Backup Type
1231	0	0	1150	Full, BSnapDiff disabled
684	106	0	577	Incremental, BSnapDiff disabled
1148	104	393	651	Incremental, BSnapDiff enabled
139	104	0	34	Incremental, BSnapDiff enabled

Results

The first two backups in this example are regular snapshot backups with the BSnapDiff Plugin installed but disabled. During the third backup, the plugin and the ZDB Setup phase are both enabled. The final Incremental is taken with BSnapDiff active and shows the improved backup performance.

An Incremental backup with BSnapDiff enabled runs is 3x to 5x faster than an Incremental backup with the feature disabled. This performance gain is primarily achieved by eliminating the overhead of reading unchanged directories and performing stat operations on a large number of unchanged files. Reducing unnecessary metadata lookups also helps keep file system caches cleaner, improving response times for other users of the file system.

These tests were performed on virtual machines running on SSD storage. Each system functioned as an all-in-one Bacula test environment, with the Director, Storage Daemon and File Daemon running locally. The ZFS file system was created as a flat file with /bin/dd. In a large production environment, a single ZFS server may host multiple, large file systems and millions or even billions of files. In such cases, performance improvements can be even more significant. For example, at one customer site, a regular Incremental backup that previously required 14 hours was reduced to just one hour with BSnapDiff enabled.