Backup Larger than Source

[Matt_R]

Hello,

My organization is using BackUp Exec 12 and have noticed that on more than one occasion our weekly backup is actually larger than the source data that it is backing up.

For instance, last week, we backed up 821 GB of data.  Upon reviewing the job, we noticed that the backup consumed 2 full tapes and a partial of a 3rd tape, which we have never experienced before, totaling just over 840 GB.  389 GB each on tapes 1 & 2,  and 62 GB on the 3rd tape. 

We do not use our weekly to backup our Exhange server, so I'm curious how the data actually grew in route to the backup tapes.

Any input would be great.

Thanks,

Matt

[ZeRoC00L]

The 821 GB of data, does it also include logs like Exchange and SQL ?

Do you create GRT backups? Or do you backup the Exchange Information Store and Mailboxes individual ?

[Colin_Weaver]

If you have a system state and C: in the same job there is the possibility for a small amount of overlap - however you should regularly see this

[pkh · Accepted solution]

If you are backing up compressed data like zipped files, sound and movie clips and has enabled compression, i.e. compressing data that is already compressed, you can end up with more data than you have started.  See my article below for an explanation.

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