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Title
Tape Drive Compression and what controls it. -
Description
Backup data is not being compressed on to Media. Native capacity is used. Compression of this data to the media does not appear to be working.
There seems to be some confusion on who/what controls compression on a tape drive.
NetVault does not do the compression. This is all done by the tape devices.
Tape devices come with compression built in. It is usually 90% of the time enabled by default.
If you experience data sent to tape media that is not compressed it is because the drive is not compressing the data. It is either not enabled on the drive or the drive itself and/or firmware is malfunctioning.
Control of data compression is handled with the Tape drive itself. Any failures to compress data would be related to the type of Media being used, or problems with the Tape device and/or firmware itself.
Furthermore, not all data compress at the same ratio. The compression ratio achieved is affect by many factors including :
type of data
Location of data
Quality of media used
Quality of the tape drive
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Resolution
Here are some areas to check:
1. Check the Library (if the tape device is installed in one), to see if the Library has locked the compression disabled.
2. Check the drive itself to see if it is disabled. By default Tape Drives should come preset from the manufacturer with compression already enabled.
3. Certain Drive manufacturers have tape devices with DIP switches that require manual intervention in setting them up to provide compression.
4. Consult your tape drive manufacturer to enable compression or troubleshoot the device.5. The drive firmware may also be corrupt. Try upgrading the tape library and drive(s) firmware to the latest version(s).
One further note. When you add a tape drive into NetVault as a device,
NetVault will actually send a SCSI command inquiry to the drive asking for it to enable compression. The Tape Drive manufacturer will already have compression enabled by default.
Hardware settings will always supersede software settings. -
Additional Information
BakBone SFDC Solution Number: 00001557