Perso, je me suis fait un petit script powershell qui fait le ménage dans les backups de LR : suppression des sauvegardes datant de plus de 30 jours, en en conservant au moins 5. (Ces 2 valeurs sont bien sûr modifiable dans le script). Sur ma machine, ce script est exécuté automatiquement tous les jours.
Pour ceux que ça intéresse, voici le script :

#%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%
# Script Suppression LR Backup
# Written by P.Coudé
# Version 1.0
# Last update : 30/01/2019
#
# Purpose
# =======
# This script will remove all but the n most recent LR catalog backup
# files, providing they are old enough.
# If a backup file has been created less than 30 days ago it won't be
# deleted anyway.
# The number of files to keep is defined in $FilesToKeep
# The oldest aging to keep is defined in $lastmod
#%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%

# Declaring variables

#$mypath = "S:\Temp\testremove\test"
$mypath ="S:\Sauvegarde\Catalogue_LR"
$FilesToKeep =5# Minimume number of files to keep
$jour = Get-Date
$lastmod = $jour.AddDays(-30) # Minimum aging days for the file to be removed


# Suppress all but the "$FilesToKeep" most recent files,
# providing the files are old enough.
$Count =0
Get-Childitem $mypath -file -recurse | Sort-object LastWriteTime -Descending |Foreach {
$Count = $Count +1
IF ($Count -gt $FilesToKeep) {
IF ($_.LastWriteTime -le"$lastmod") {
# write-host "Deleting File" + $_.fullname -foregroundcolor "Red";
Remove-Item $_.fullname | out-null
}
}
}
# Suppress the empty folders
$ListFolder = Get-Childitem $mypath -Directory -recurse |where { @(gci $_.Fullname).count -eq0}
Foreach ($Folder in $ListFolder) {
Remove-Item $Folder.Fullname -Recurse | out-null
}

# End of script