LTO3 Compression

[IS1]

Some background...  We have an Overland ArcVault 800, 24 tapes, 1 drive.  Symantec BackupExec 11d.

We are running LTO3 "800GB" tapes.  As I understand it, these tapes are 400GB tapes in "native mode" and 800GB with compression.  I will never actually see the tapes' capacity extend to 800GB because of compression variables.  But it should AT LEAST expand a little beyond 400GB.  On the contrary, I am getting 391GB out of every tape.  How can this be changed?  How can I get better functionality out of the ArcVault?

[pkh · Accepted solution]

Compression is dependent on the data that is being compressed.  If you are compressing data which is already compressed like zipped files, movie and sound clips, then you can end up with more data that you first started.  See my article on this subject.

https://www-secure.symantec.com/connect/articles/compression-short-explanation

[IS1]

Well...  That is good info...  I'll give up on getting anything beyond this 391GB.  Thanks again.