Repository growing faster than anticipated

Our repository is growing faster than anticipated.  I'm curious if there are any tools / methods available to try to get a grip on why...?  It could be deduplication not working as well as desired, or repository cleanup not actually cleaning up, or I simply may need to add additional storage.  I'd like to be able to investigate before adding more storage.

We have a 10 GB dedup cache on a backup/core server with 32 GB of memory.

We are running RR 6.0.2.144.  The core is Windows 2008 R2 Std.  We have approximately 14 TB of usable storage for RR on a SAN, and it is currently using 10.5 TB and growing at a rate of about 1 TB per month.

I have tried Repository Optimization.  Unfortunately, it runs incredibly slow and consumes pretty much all resources for RR during its run, causing backups/rollups/checks to take so long that they fail.  I'd be willing to pause everything for an Optimization task, if it could complete over a holiday weekend.  Unfortunately, in two days it will complete less than 10% of an optimization job.  I simply cannot halt all backups for a month (or more) for it to run an optimization. 

I'd also like to track repository usage over time.  Is there any log showing that, so that I do not have to manually keep a written log of repository usage?

 

Thank you