Image sizes on Windows vs Ubuntu host

Server
1

I am testing UrBackup on different platforms, one running Windows 10 and one running Ubuntu.

The Ubuntu server is storing the backups on a btrfs partition, whereas Windows is using NTFS.

The issue I am seeing is that the backups on the Ubuntu server are taking up considerably more space than those on Windows, each incremental backup that runs is showing the full size again, rather than just the incremental amount, here are some logs to show my issue:

24 Luke-PC Incremental image backup Volume: C: 11/04/19 11:53 10 min 77.43 GB
13 Luke-PC Incremental image backup Volume: C: 10/04/19 17:10 13 min 77.47 GB
11 Luke-PC Full image backup Volume: C: 10/04/19 16:36 34 min 77.43 GB

Luke-PC 155 GB 0 bytes 155 GB

But live logs state

11/04/19 08:51 INFO Basing image backup on last incremental or full image backup
11/04/19 08:51 INFO Creating writable snapshot of previous image backup…
11/04/19 10:22 DEBUG Starting trimming image file (if possible)
11/04/19 10:22 DEBUG Trimmed 837.5 MB
11/04/19 10:22 INFO Transferred 4.02268 GB - Average speed: 6.30829 MBit/s

Windows hosted client states:

20 Server Incremental image backup Volume: C: 11/04/19 08:47 58 min 1.74 GB
15 Server Full image backup Volume: C: 09/04/19 22:52 1358 min 110.99 GB

|Server|111.61 GB|0 bytes|111.61 GB|

11/04/19 08:47 INFO Basing image backup on last incremental or full image backup
11/04/19 09:45 INFO Transferred 1.60462 GB - Average speed: 3.99374 MBit/s
11/04/19 09:45 INFO (Before compression: 3.37858 GB ratio: 2.10553)
2

It doesn’t actually use that much storage on btrfs. Getting the actual storage used is just hard and costs a lot performance. You could look at overall storage usage and how much it drops with a backup to get an idea how much it uses. Or you can enable btrfs quotas and look at subvolume sizes, but that makes btrfs significantly slower.
You’ll have the same problem on Windows if you use the Windows server deduplication.

3

I found this script which calculate the true size https://ownyourbits.com/2017/12/06/check-disk-space-of-your-btrfs-snapshots-with-btrfs-du/

What it’s told me is that I’m only using 300GB actual space when urbackup reports 491.63 GB in it’s interface, I can see why its difficult to display the real size as the script took about half an hour to run quotas to figure it all out.

At least I know its working as it should.