So, I have a current Reverse Incremental job set up. It's my nightly backup job that has a 6 day retention. I've been asked to figure out how much storage I would need to add in a Monthly backup for 1 year and I'm trying to calculate the size based off of what I know from my existing nightly job.
Here is what my nightly job looks like:
So, with a 5% per day change rate, would I just calculate that out x 30 days (or so) to get a total amount of change rate if I set up the following job or would the change rate math not really work out the same due to me only running the job once per month?:
If your backup job will run only once per month, surely the change rate will be higher than 5%, but I would not calculate however 0.4TB * 30 to get the final size of a monthly change rate, because in this way you are missing the updated blocks: some blocks will be written over and over again multiple times, but during the backup only the last version of it will be saved into the incremental.
So, for sure the final size of the monthly incremental will be smaller than (in your case) 12 TB, but it's hard to tell what will be the actual size.
Luca Dell'Oca Principal EMEA Cloud Architect @ Veeam Software
In addition to what Luca has posted above, I would suggest taking a look at Veeam ONE predefined reports (Backup files growth and Capacity planning for backup repositories) that can you give you some insight on backup files growth and their change rate. Just my 2 cents.