Backup Exec 12.5 did not compress my LTO-2 tape

[Max_2]

Hi,

I have a Backup Exec 12.5 SP4. When I set up a backup job with compress type --"software" The ratio always shows 1:1. The tape did not get compressed at all. The compress option was checked under drive property. I also use software encryption during the backup. Will be the cause encrypted date not able to be compressed or some other reasons? Any suggestion is appreciated. Thanks.

[Ken_Putnam]

Encrypted data can actually lead to a less than 1:1 compression ratio.

When using Encryption, you should turn compression off

[Max_2]

Hi Ken,

With data Encryption, I have no way to get tape compression. right?

[VJware · Accepted solution]

This should answer - http://www.symantec.com/docs/TECH135848

[pkh]

No.  This is not true.  You can use software compression if you are using software encryption.  If you are using hardware encryption, then you can use hardware compression.  If you are using both these combinations and still do not see any compression, then it could be that you are backing up compressed data, like zipped files, etc.  See my article on this subject.

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

You can try doing a backup with just compression and see what the compression ratio is.

Note that you should not use hardware compression with software encryption.

[Max_2]

Thanks for your article. It has been helpful. Basically we do the full server backup which contains various of data. hence compressed date and zipped files have been ruled out from my case. We used to compress data without encryption. It did compress data well, (sometome ration go more than 2:1) but recently we changed the security policy to encrypt the data before backup. the ration now is 1.1:1. It only compress data a little bit. That was the reason I raised this post to clarify my doubt. Do you think this is a natual of Symantec thing?

Note: We use both software encrytion and compression, there is no hardware encrytion and compression.

[pkh]

Basically we do the full server backup which contains various of data. hence compressed date and zipped files have been ruled out from my case.

If you do have zipped files and other compressed data on your server, doing a full server backup will not exclude them, unless you specifically do the exclusion.

In my tests, I found that turning on encryption have only a small effect on my compression ratio, i.e. it dropped from 1.3 to 1.2.

It could be that your data mix have changed, e.g. some users may have stored some sound or movie files on your server.  You should try doing the same backup without encryption and compare the compression ratio.