Compression and NetBackup performance
NetBackup supports two types of compression:
Client compression (configured in the NetBackup policy)
Tape drive compression (handled by the device hardware)
Consider the following when choosing the type of compression:
If backup goes to MSDP, which does data compression by default, the client compression should not be enabled. Enabling the client compression may lead to poor deduplication rate in addition to potential performance impacts.
The decision to use data compression should be based on the compressibility of the data itself.
Note the following levels of compressibility, in descending order:
Plain text
Usually the most compressible type of data.
Executable code
May compress somewhat, but not as much as plain text.
Already compressed data
Often, no further compression is possible.
Encrypted data
May expand in size if compression is applied.
Tape drive compression is almost always preferable to client compression. Compression is CPU intensive, and tape drives have built-in hardware to perform compression.
Avoid using both tape compression and client compression
Compressing data that is already compressed can increase the amount of backed up data.
Only in rare cases is it beneficial to use client (software) compression
Those cases usually include the following characteristics:
The client data is highly compressible.
The client has abundant CPU resources.
You need to minimize the data that is sent across the network between the client and server.
In other cases, however, NetBackup client compression should be turned off, and the hardware should handle the compression.
Client compression reduces the amount of data that is sent over the network, but increases CPU usage on the client.
On UNIX, the NetBackup client configuration setting MEGABYTES_OF_MEMORY may help client performance.
This option sets the amount of memory available for compression.
Do not compress any files that are already compressed. If the data is compressed twice, refer to the NetBackup configuration option COMPRESS_SUFFIX. You can use this option to exclude files with certain suffixes from compression. Edit this setting through
bpsetconfig.See the NetBackup Administrator's Guide, Volume II.
More Information
Effect of encryption plus compression on NetBackup performance