SQL Server Backup and Restore - Simple Talk

Chapter 8: Database Backup and Restore with SQL Backup Pro
Figure 8-7 compares these metrics to those obtained for identical operations using native
backup, compressed native backup, as well as SQL Backup using a higher compression
level (3).
Backup Operation Backup File Size
in MB (on disk)
Native Full 501 19.6
252
Backup Time
(seconds)
% Difference compared
to Native Full
(+ = bigger / faster)
Size Speed
Native Full with Compression 6.7 4.6 -98.7 +76.5
SQL Backup Full Compression Level 1 3.7 3.1 -99.3 +84.2
SQL Backup Full Compression Level 3 7.3 4.5 -98.5 +77
Figure 8-7: Comparing full backup operations for DatabaseForSQLBackups (0.5 GB).
SQL Backup (Compression Level 1) produces a backup file that requires less than 1% of
the space required for the native full backup file. To put this into perspective, in the space
that we could store 3 days' worth of full native backups using native SQL Server, we could
store nearly 400 SQL Backup files. It also increases the backup speed by about 84%. How
does that work? Basically, every backup operation reads the data from the disk and writes
to a backup-formatted file, on disk. By far the slowest part of the operation is writing the
data to disk. When SQL Backup (or native compression) performs its task, it is reading all
of the data, passing it through a compression tool and writing much smaller segments of
data, so less time is used on the slowest operation.
In this test, SQL Backup with Compression Level 1 outperformed the native compressed
backup. However, for SQL Backup with Compression Level 3, their performance was
almost identical. It's interesting to note that while Level 3 compression should, in theory,
have resulted in a smaller file and a longer backup time, compared to Level 1, we in fact
saw a larger file and a longer backup time! This highlights the importance of selecting the
compression level carefully.