I'm working with a backup program that doesn't automatically manage disk space, so I've set up a script to delete the oldest files when my disk space drops below 1 GB. Right now, my script deletes batches of 7 files, which is fine unless I mess up the backup schedule while I'm traveling. This leads to some unnecessary differential backups sticking around even after their associated full backup is deleted. I'm trying to improve my script to delete differential backup files until it finds a more recent full backup, regardless of the dates. I need help writing this PowerShell script to achieve that.
2 Answers
What have you tried so far? It might help to see your current script so we can suggest improvements.
Also, just to clarify, are you deleting based on a specific date range or just the oldest ones?
It sounds like a good plan! You could grab the latest full backup and then exclude differential backups within a specific timeframe. Here’s a quick snippet that might help:
```powershell
$latestFull = Get-ChildItem X:BKP -File |
Where-Object { $_.Name -match 'FULL' } |
Sort-Object LastWriteTime -Descending |
Select-Object -First 1
$windowStart = $latestFull.LastWriteTime
$windowEnd = $windowStart.AddDays(7)
$diffs = Get-ChildItem X:BKP -File |
Where-Object { $_.Name -match 'DIFFERENTIAL' }
$toDelete = $diffs | Where-Object { $_.LastWriteTime -lt $windowStart -or $_.LastWriteTime -gt $windowEnd }
$toDelete | Remove-Item -Force -WhatIf
```
This code will give you a start to work from!
I've been using a bunch of if statements to check the remaining size and filter files by date. I basically remove differential and full backups older than certain days.