Unsupported compressions ratios being stated by Backup Exec

[DCA-IT]

Our Backup Exec server is using LTO-6 tapes which have a maximum compression ratio of 2.5:1 in ideal circumstances, which are rarely achieved.

For some tapes, Backup Exec is quoting compression ratios of 5.77:1 and 5.33:1 (see attached screenshot)

How is this possible please?

[Gurvinder]

double click on the tape and check the number of sets that exist on that tape. compression also depends on the data being backed up. From the screenshot the tape is 418 GB full , if you go to details of tape and check the number of backup set and sum up the size of each , you would know if this is true or BE not calculating the true ratio (Sum of all sets on tape/418 for the CMB626L6 tape).

[Larry_Fine · Accepted solution]

There is no such thing as an unsupported, or maximum, compression ratio.

The 2.5:1 number quoted by the LTO manufacturers is an average (according to them).  It is used for marketing purposes.

Highly compressible data will yield very high, and valid, compression ratios.  It all depends upon the source data.

It is possible that BE is somehow reported an inaccurate compression ratio number, but that doesn't make it unsupported or illegal.

[DCA-IT]

Thanks Larry and Gurvinder for your input.