Compression Levels
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.
| Compression Level | Description |
|---|---|
| 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. |
| 7, 8 |
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). 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:
- Its important to back up the database encryption key, because there is no way to recover the data without the key. LiteSpeed does not automatically export the encryption key. If needed, you can include the encrypted key file in the backup. For more information, see Back Up Databases.
- To further protect the backup, you can use LiteSpeed Encryption with TDE databases to add a secondary layer or protection to the backup. For more information, see Encryption Methods.
Adaptive Compression
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:
- Optimize for speed—Backups complete in the least amount of time possible. Available CPU is leveraged to reduce backup size, but not at the expense of increased backup time. This is the default setting.
- Optimize for size—Backups are completed with higher compression while managing overall backup time to ensure backups do not take a long time to complete (when compared to optimizing for speed). In this mode, LiteSpeed allows the backup to complete more slowly if the reduction in speed results in a smaller backup file. This mode is designed for databases where a smaller backup is desired but managing how long the backup takes to complete is important as well.
NOTE: Adaptive Compression is only available with LiteSpeed 6.5 or later; Enterprise license.
Encryption
Encryption is a mechanism for protecting data, which applies to it a specially designed algorithm, effectively obfuscating its content by making it different from the original.
NOTE: If running Windows 2000 to utilize the higher levels of encryption, the Windows 2000 High Encryption Pack must be installed.
LiteSpeed offers the option of encrypting in the following formats:
-
40-bit RC2
-
56-bit RC2
-
112-bit RC2
-
128-bit RC2
-
168-bit 3DES
-
128-bit RC4
-
128-bit AES
-
192-bit AES
-
256-bit AES
- 128-bit AES Microsoft implementation (MS_AES_128)
- 192-bit AES Microsoft implementation (MS_AES_192)
- 256-bit AES Microsoft implementation (MS_AES_256)
Higher levels of encryption require slightly more CPU, but generally the impact of 256-bit AES encryption on a backup running on a modern server is very low at less than 0.5% CPU utilization. We recommend for best security of a backup that 256-bit AES be used when encryption is needed.
Caution: When encrypting data, take care not to lose the encryption key; a backup cannot be restored or recovered without the original encryption key.
Double-Click Restore Executables
A Double Click Restore is an executable that has an .exe extension and performs a database restore when double-clicked. An executable file allows you to restore a backup on a server instance that does not have LiteSpeed installed.
A Double Click Restore executable is created by either writing a loader program designed to restore backup files, or by inserting the loader directly into the header of a suitable LiteSpeed backup file. If you convert a striped backup file, the first file will be the executable (.exe), and the others will remain unchanged.
Double Click Restore Naming Conventions
Double Click Restore conversion may modify the extension of the backup file.
For LiteSpeed backups, file name conversion depends on whether you create a double click restore loader. By default you will create a double click restore loader. The backup file name will not have the .exe extension and LiteSpeed will create X.exe, the empty Double Click Restore loader that restores the backup when double-clicked. If you do not create a double click restore loader then the backup file name will have the .exe extension.
For native SQL Server backups, LiteSpeed will create the empty Double Click Restore loader that has the .exe extension and restores the backup when double-clicked.
| Backup Type | Name Before Conversion | Name After Conversion |
|---|---|---|
|
Create one Double-Click Restore executable file. The executable may be greater than 4GB for large databases. Windows Server is unable to run executable files larger than 4GB. However, the file will be convertible/restorable by LiteSpeed file. @doubleclick = 1 |
X.exe |
X.exe (No name changes) |
| X | X.exe | |
|
Create a Double Click Restore Loader (Default). @doubleclick = 2 |
X.exe |
X* |
| X |
X* (No name changes) | |
| Native SQL Server | X.exe |
X* |
| X |
X* (No name changes) | |
|
*—X.exe is created as empty Double Click Restore loader. You can locate it in the same directory as the converted X. | ||
Create Double Click Restore Executables
To create a new Double Click Restore executable, do one of the following:
- Select the Create a Double Click Restore executable... option when creating backups in the LiteSpeed UI Console.
- Supply @doubleclick = 2 when creating a backup using procedures. For more information, see xp_backup_database.
- Supply --doubleclick 2 when creating a backup using command-line interface. For more information, see LiteSpeed Command-Line Arguments.
|
Scenario You need to restore particular compressed and encrypted LiteSpeed backups on a server that does not have LiteSpeed
|
Click hereTo restore LiteSpeed backups on a server that does not have LiteSpeed
- Define which backup files are needed for the restore and convert them to the Double Click Restore executables. Do one of the following:
- Right-click a backup in the Backup Browser tab or in the Backup History tab and select Convert to Double Click Restore backup.
-
Run exec xp_slsCreateDCR @FileName='<path>'
where <path> is the path to the backup.
-
Copy the Double Click Restore executable(s) you created to the server that does not have LiteSpeed.
NOTE: If a backup file is more than 4 GB, you need to copy both the converted backup file and the empty Double Click Restore loader.
-
Log on to the server, double-click the first Double Click Restore Executable file to restore and complete the LiteSpeed Double Click Restore dialog. Repeat for all other files.
NOTE: If you deselected and selected appended backups to restore, you may need to re-enter the encryption password.
Network Resilience
LiteSpeed's read and write resilience can handle various failures on both network and attached storage devices. If LiteSpeed fails to write a backup during a backup operation or fails to read a backup during a restore operation, it will wait and retry the failed operation. If successful on a subsequent attempt, the backup or restore operation continues without interruption. Without network resilience, these operations would fail immediately on the first read or write problem encountered.
You can control the number of times to retry and the amount of time to wait before retrying.
To configure retry options in wizards
- Access advanced options.
- Select one or both network resilience options to change the default values.
- Complete the wizard.
To configure retry options in procedures
Use @IOFLAG parameter. For more information, see About Using Extended Stored Procedures.
To configure retry options from the command line
Use -X or --IOFlags parameter. For more information, see LiteSpeed Command-Line Arguments.
NOTE: LiteSpeed makes 3 attempts for creation of the backup folder at 0.5 second intervals. This is not configurable.