You can specify a compression level manually, or you can use Adaptive Compression to let LiteSpeed automatically select the optimal compression level. For more information, see Adaptive Compression.
LiteSpeed offers the following compression levels that allow you to specify compression from least compression to most compression, with a corresponding CPU trade-off.
|1||Medium Compression—for servers where minimal CPU utilization is preferred at the expense of some compression.|
|2||Medium-High Compression—a new highly optimized low CPU algorithm for environments where low CPU utilization is preferred but with improved compression over level 1.|
|3, 4, 5, 6||High Compression—for databases where balanced compressed backup size and CPU utilization is important.|
Extreme Compression—a new highly optimized extreme compression algorithm for databases where compressed size is very important with only a slight increase in CPU utilization over previous levels.
NOTE:Levels 9, 10 and 11 were deprecated in version 6.0 and are now automatically mapped to the new compression level 8.
Depending on your environment, the various algorithms will yield different results. When choosing a compression level, test various options to determine the best option for your environment. For more information, see Test Optimal Backup Settings.
Generally, the higher the compression ratio the higher the CPU utilization and potentially more compression. That is, the higher compression levels will look for longer patterns to compress, as well as perform more passes on the data.
The higher levels do not guarantee better compression ratios as the nature of the data dictates the final result. Therefore, some databases will get varying results as the level increases.
Additionally, if a higher level gets significantly better compression, it may actually perform faster than a lower level. Typically, the higher levels require more time for the backup.
NOTE: LiteSpeed supports backing up, restoring and shipping transaction logs of the databases encrypted with transparent data encryption (TDE). Since the database is encrypted with TDE, the LiteSpeed backup will not compress very well. If you want to compress the backup, you should choose compression level 1 to minimize CPU, since using a higher level of compression will only cause CPU to increase without any real benefit on the backup file size. If you choose compression level 0, LiteSpeed will not attempt to compress the backup. Review the following for additional information:
With Adaptive Compression you do not have to run the Backup Analyzer wizard to determine the best compression level for a database. LiteSpeed will dynamically change the compression level during a backup in order to optimize for speed or size, while maximizing use of available CPU. If the server workload changes during the backup (change in CPU or Disk IO), Adaptive Compression automatically switches compression to maintain optimal performance.
You can select to optimize backups either for size or for speed:
NOTE: Adaptive Compression is only available with LiteSpeed 6.5 or later; Enterprise license.