Slow Speed When Copying a Backup to Tape
Product version: 10.8
Last modified: 22 December 2022
When copying a backup from a Backup Repository to a tape device, the data transfer speed is significantly slower than normal.
This issue may be caused by a difference in compression levels between the repository and tape device. If the repository and tape have different compression levels, the backup copy job will be slowed down due to decompression/recompression of the backup data. When copying compressed backups to tape, it is recommended to use the same level of software compression as the source repository. In addition, it is recommended to enable network acceleration for the backup copy job.
To set the same level of software compression for the tape device, follow the steps below:
First, check the compression settings on the repository containing the backup by going to Settings > Repositories and clicking on the repository name. Make a note of the compression level denoted by the Compression parameter.
Next, check the compression settings on the chosen tape device by going to Settings > Tape and clicking on the tape device name. Make a note of the compression level denoted by the Compression parameter.
If the tape device compression settings don't match those of the repository, you will need to reconfigure the tape device with a corresponding software compression level. To reconfigure the tape device, re-add it to the Tape tab in Settings by going through the wizard for Robotic Tape Libraries/VTLs or Standalone Tape Drives. In the Compression drop-down on the Select Options step, select the software compression level that corresponds to that of the repository containing the compressed backup. See the table below for corresponding Backup Repository/tape device compression settings.
Backup Repository Compression Level Tape Device Compression Level Fast Software-based (fast) Medium Software-based (medium) Best
Next, make sure that Network Acceleration is enabled for the backup copy job. Click on the job in the Jobs dashboard, click Edit, go to the Options step, and check that Network Acceleration is set to Enabled.
Try running the backup to tape again. You may need to erase tape cartridges on the chosen tape device and format them with the correct compression level.