Backup to zip

I wanted to have a tool that creates a backup to a zip file, but I didn’t want the zip file to be recreated every time (as it can take nearly a day for some backups I wanted to make), thus I need something to synchronize to zip and remove items from the zip archive if they are removed from disk. If I restore a backup and the folder I want to backup had an older file than the zip archive contains, the folder with the older file should be leading and the file in the zip archive needs to be overwritten.

I decided the best way to go would be the dos/commandline version of 7zip (7za.exe), which you can download from their sourceforge. Be warned that splitting in volumes doesn’t work in this case, because the update to zip function won’t work.

How to use this tool with synchronize options, I found here. But as this treats newer files as leading, I did need to tweak it a little bit, so the folder would be the leading factor.

I also needed to exclude the folder called “backups” and don’t want the other zip files which I created backupped into this zip file, thus I need to exclude all files which start with the name “backup” as well. As I like to create a log file as well, I also include the date. (could have used start-transcript as well, which I usually use and I believe is a better way for creating log files. I don’t know why I didn’t use it this time)

Get-Date | Out-File D:\Data\Backup.log
& "$PSScriptRoot\7za.exe" u -tzip "D:\Data\Backup.zip" -up1q0r2x2y2z1w2 D:\Data\* -mx7 '-xr!Backups' '-xr!Backup*.*'  >> D:\Data\Backup.log
Get-Date | Out-File D:\Data\Backup.log -Append

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