Problems with incremental backups and deduplication

Server
1

Hi,

I seem to have two issues with an incremental backup. For some reason some files are backed up from client every single time even though they have not changed. And what is worse, they do not seem to be deduplicated on the server side either, although my understanding is that urbackup should do that. There are a lot of them and that will mount up to long backup times and lots of wasted storage.

Server - Centos Linux, UrBackup 2.3.8 on BTRFS file system
Client - Windows 10, UrBackup 2.3.4

For example, stat on the server side of the same file from two different incremental backups (sensitive info masked with @@@@@@):

# stat "/mnt/urbackup/DESKTOP-@@@@@@@/190718-1003/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi"
  File: ‘/mnt/urbackup/DESKTOP-@@@@@@@/190718-1003/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi’
  Size: 2341675008	Blocks: 4573584    IO Block: 4096   regular file
Device: 90006eh/9437294d	Inode: 134593      Links: 1
Access: (0750/-rwxr-x---)  Uid: (  497/urbackup)   Gid: (  500/urbackup)
Access: 2019-05-14 17:50:43.000000000 +0300
Modify: 2019-05-14 17:50:43.000000000 +0300
Change: 2019-07-16 10:02:57.701809131 +0300
 Birth: -


# stat "/mnt/urbackup/DESKTOP-@@@@@@@/190722-1707/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi"
  File: ‘/mnt/urbackup/DESKTOP-@@@@@@@/190722-1707/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi’
  Size: 2341675008	Blocks: 4573584    IO Block: 4096   regular file
Device: 1b000eah/28311786d	Inode: 134593      Links: 1
Access: (0750/-rwxr-x---)  Uid: (  497/urbackup)   Gid: (  500/urbackup)
Access: 2019-05-14 17:50:43.000000000 +0300
Modify: 2019-05-14 17:50:43.000000000 +0300
Change: 2019-07-16 10:02:57.701809131 +0300
 Birth: -

md5sum seems to be the same as well:

md5sum "/mnt/urbackup/DESKTOP-@@@@@@@/190718-1003/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi"
149b39e539e708f19b17cba00ac56505  /mnt/urbackup/DESKTOP-@@@@@@@/190718-1003/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi

md5sum "/mnt/urbackup/DESKTOP-@@@@@@@/190722-1707/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi"
149b39e539e708f19b17cba00ac56505  /mnt/urbackup/DESKTOP-@@@@@@@/190722-1707/Users/@@@@@@@/Videos/@@@@@@@/@@@@@@@.avi

Any ideas, what can i do to debug this?

2

On btrfs it uses reflinks instead of hard links. So you’d have to look at the files with e.g. filefrag -v filename and look if extents are the same + shared.