Backup to USB showing less data than expected

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Backup to USB showing less data than expected

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I've used Hyper Backup to backup my entire NAS (DS 218J) to a USB drive using the Local (single version option) and it copied the full 2.5TB of data to the USB drive. However when I use the Local (multi-version option) with encryption I get a backup size of just 1.4TB - what's going on?

I know I have duplicate files on the NAS but I'd be surprised if it was 1.1TB worth of data. I'm not running compression on the backup either so am concerned some files are not getting backed up. Any way I can check what is happening, and does this seam normal? Could it be duplicates, if so how can I check to be sure? Why did the other backup option result in a 2.5TB backup and this one only 1.4TB? Sorry I'm really confused.

My plan was to take the multi-version encrypted USB drive off-site (leaving it in my work locker) as an off-site backup - hence wanting to keep it encrypted, bringing it back from time to time to update the backup. So I want to ensure this is really a full backup of my drive.

Hi, welcome to the forum.

Someone with more knowledge may jump in. I'm not sure how much of the the package data, e.g. Synology Drive Server, would be backed up and it has it's database of versioned files. There's also recycle bins.

Check how much is in these. There's an option in Drive Server to calculate how much space it's using, and it's no way as efficient at using space on an ext4 file system as it is on Btrfs.

If you have selected everything for the HB task to backup, i.e. all packages and all shared folders, then you'll have as complete a backup as is possible.

May be if you explain what packages and DSM features you are using, plus storage setup, then that will point to something else.
All the data was copied to the Synology NAS from an old WD MyBook Live device so I'm not yet using Drive Server. I've installed it but not started using it to sync the laptop & desktop PC to the Synology yet.

Only other service I've installed on the DS218J is Plex. I've only had the NAS for a couple of weeks and haven't started deleting stuff from the drive yet so unlikely recycle bin is a factor.

I'm simply comparing the size of data on disk as reported by the NAS (2.5tb) to the size of the backup as reported by HyperBackup. I can't understand why such a big difference.

I've formatted the Seagate USB hard disk as ext4 as well instead of the default NTFS that it came formatted as. Did this in case the backup was failing to copy files due to the limitations of the file paths/length/characters etc. Its made no difference to the final backup size (although switching to ext4 did seem to speed up the backup - could be coincidental though).
Did you enable compression?
Did you enable compression?
View attachment 4186

No, I didn't enable compression (I only have a DS218J and it seems to slow down the backup if encryption is enabled so adding more processing requirements for compression seemed like a bad idea lol)

I see in the Hyper Backup guide there is mention of a Deduplicate option but that doesn't appear as a checkbox when setting up the backup.

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