If you are going to backup to the cloud (over an internet connection) you will typically first do a full backup, then do incrementals from then on. Most cloud vendors charge for how much data you store and/or send daily. You also want to know this information to determine if your bandwidth can handle the amount of data during the backup window (typically overnight) that you have available.
How can you estimate the average volume of data that changes on your busy network in an average day? We wrote a incremental backup calculator with instructions here that will do it for you. Or, let me show you 6 easy steps to calculate data changed per day for backup. We will use Windows Explorer either directly on the server or from a workstation.
- Login as administrator so you have rights to see all files. Open Explorer and make sure it is set to display hidden and system files. Otherwise Explorer won’t include these and your calculations may be off.
- Click the magnifying glass or search option (see picture or video)
- Choose a data range (recommend at least a week but month is probably better) and hit enter
- Wait for Windows to display all files/folders modified in that date range.
- Select only Files (Ignore folders or you will get a double count) by clicking the first one, scroll to bottom, hold down Shift and click the last one
- Right mouse click and select properties. The total size of files changed over that period will be displayed. Now just divide the total size by the number of days you selected in step 3 to get a daily average.
The number you calculate should be a worst case scenario. If you are looking at your C: or system drive you may wish to exclude hiberfil.sys and pagefile.sys from the above file selections in step 5 (or manually subtract them from the total in step 6). These files can be quite large and will always show up as changed if you have explorer set to show hidden and system files.
If your backup software does file level incrementals the estimate should be close. If your software is more sophisticated and does block level incrementals, it will be high. To understand why, imagine you open a large file, change one character, and save it. A block level incremental backup program will transmit just 1 block. This could be considerably less than the size of the entire file, which is what you’d have to transmit using a file level incremental backup system.
The video below does a walk through of the steps outlined. If you have difficulty viewing the video try the YouTube link: http://youtu.be/UoQ8ZfvOOds