Disk Rate Change Calculator

Disk Rate Change Calculator: Have you ever wanted a way to know how many files, on average, change on your network per day? This is crucial to estimating how big your nightly incremental backup will be. We first provided a way to do this in our blog post 6 Easy Steps to Calculate Data Changed Per Day for Backup. We wanted to provide a more automated, scriptable way to do this calculation so we wrote the incremental backup calculator.   Since it uses Cscript just open a CMD window and use the general form

Cscript bsize.vbs J: 10/01/2013 10/31/2013

where you will change J: to your network drive letter or path and the dates to match a range you want to scan for modified files.   The program automatically skips system files like hiberfil.sys and pagefil.sys that can be quite large and really throw your results off. As mentioned in the blog post above, this should be a “worst case” number, because it reflects total file sizes rather than modified blocks but it should help you get an idea how big your changes will be.

Don’t forget to divide the total size returned by the number of days you scanned to get an average per day. You could skip weekends if you want to analyze only weekdays by providing the script week day ranges.

if you add /Verbose the command will list the folders as it scans and show you which files matched. Use the typical trick of using a greater than symbol at the end of the command line to redirect screen output to a text file if you want to create a log of the results. If you do this nothing will display on the screen so be patient for it to finish. The text file can be useful with a wordprocessor or wordpad to search for certain files after the script finishes. Example:

Cscript bsize.vbs /verbose J: 10/01/2013 10/31/2013 >logfile.txt