Backup much bigger than root filesystem

I recently moved my docker containers from my root drive to another drive. My backups are no smaller. I'm using fsarchiver in omv system/backup. My root drive is only using about 8GB according to multiple utilities, including du, but fsarchiver is creating a backup that's 60GB.

It has to be backing up stuff that's not on that drive, or perhaps deleted files? What can I do to make my backup size reflect the actual disk usage?

Thanks for the reply. Here's the log from yesterday's backup:

[2024-03-23 01:00:01-0400] [backup] Starting backup...

[2024-03-23 01:00:01-0400] [backup] Create /srv/dev-disk-by-uuid-4752abb9-f21f-408c-a38b-efdb2bf69182/bak/omvbackup

[2024-03-23 01:00:01-0400] [backup] Method: fsarchiver

[2024-03-23 01:00:01-0400] [backup] Device file: /dev/sdc1

[2024-03-23 01:00:01-0400] [backup] Root drive: /dev/sdc

[2024-03-23 01:00:01-0400] [backup] Save fdisk output for /dev/sdc

[2024-03-23 01:00:01-0400] [backup] Successfully saved fdisk output for /dev/sdc

[2024-03-23 01:00:01-0400] [backup] Save blkid output

[2024-03-23 01:00:01-0400] [backup] Successfully saved blkid output

[2024-03-23 01:00:01-0400] [backup] Save package list

[2024-03-23 01:00:01-0400] [backup] Successfully saved package list

[2024-03-23 01:00:01-0400] [backup] Partition type :: dos

[2024-03-23 01:00:01-0400] [backup] Save mbr

[2024-03-23 01:00:01-0400] [backup] Successfully saved MBR

[2024-03-23 01:00:01-0400] [backup] Save mbr and partition table

[2024-03-23 01:00:01-0400] [backup] Successfully saved MBR and partition table

[2024-03-23 01:00:01-0400] [backup] Save partitions using sfdisk

[2024-03-23 01:00:01-0400] [backup] Successfully saved partition table using sfdisk

[2024-03-23 01:00:01-0400] [backup] Starting FSArchiver backup...

[2024-03-23 01:20:16-0400] [backup] FSArchiver backup complete.

[2024-03-23 01:20:16-0400] [backup] keep days :: 5

[2024-03-23 01:20:16-0400] [backup] Purging old files...

[2024-03-23 01:20:16-0400] [backup] Purging done.

[2024-03-23 01:20:16-0400] [backup] Backup complete.

output of the backup folder:

total 115G
drwxrwsr-x+  2 root users 4.0K Mar 24 14:33 .
drwxrwsr-x+ 15 root users 4.0K Oct 15 09:10 ..
-rw-rw-rw-+  1 root users  800 Mar 21 01:18 backup-omv-2024-03-21_01-00-01.blkid
-rw-rw-rw-+  1 root users  550 Mar 21 01:18 backup-omv-2024-03-21_01-00-01.fdisk
-rw-r--r--+  1 root users  56G Mar 21 01:18 backup-omv-2024-03-21_01-00-01.fsa
-rw-rw-rw-+  1 root users  446 Mar 21 01:18 backup-omv-2024-03-21_01-00-01.grub
-rw-rw-rw-+  1 root users  512 Mar 21 01:18 backup-omv-2024-03-21_01-00-01.grubparts
-rw-rw-rw-+  1 root users 2.1K Mar 21 01:18 backup-omv-2024-03-21_01-00-01.packages
-rw-rw-rw-+  1 root users  267 Mar 21 01:18 backup-omv-2024-03-21_01-00-01.sfdisk
-rw-rw-rw-+  1 root users  800 Mar 23 01:20 backup-omv-2024-03-23_01-00-01.blkid
-rw-rw-rw-+  1 root users  550 Mar 23 01:20 backup-omv-2024-03-23_01-00-01.fdisk
-rw-r--r--+  1 root users  56G Mar 23 01:20 backup-omv-2024-03-23_01-00-01.fsa
-rw-rw-rw-+  1 root users  446 Mar 23 01:20 backup-omv-2024-03-23_01-00-01.grub
-rw-rw-rw-+  1 root users  512 Mar 23 01:20 backup-omv-2024-03-23_01-00-01.grubparts
-rw-rw-rw-+  1 root users 2.1K Mar 23 01:20 backup-omv-2024-03-23_01-00-01.packages
-rw-rw-rw-+  1 root users  267 Mar 23 01:20 backup-omv-2024-03-23_01-00-01.sfdisk
-rw-rw-rw-+  1 root users  800 Mar 24 14:55 backup-omv-2024-03-24_14-30-08.blkid
-rw-rw-rw-+  1 root users  550 Mar 24 14:55 backup-omv-2024-03-24_14-30-08.fdisk
-rw-r--r--+  1 root users 3.0G Mar 24 14:55 backup-omv-2024-03-24_14-30-08.fsa
-rw-rw-rw-+  1 root users  446 Mar 24 14:55 backup-omv-2024-03-24_14-30-08.grub
-rw-rw-rw-+  1 root users  512 Mar 24 14:55 backup-omv-2024-03-24_14-30-08.grubparts
-rw-rw-rw-+  1 root users 2.1K Mar 24 14:55 backup-omv-2024-03-24_14-30-08.packages
-rw-rw-rw-+  1 root users  267 Mar 24 14:55 backup-omv-2024-03-24_14-30-08.sfdisk

and fdisk:

Disk /dev/sdc: 111.79 GiB, 120034123776 bytes, 234441648 sectors
Disk model: KINGSTON SV300S3
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x2519832c

Device     Boot     Start       End   Sectors   Size Id Type
/dev/sdc1  *         2048 232441855 232439808 110.8G 83 Linux
/dev/sdc2       232443902 234440703   1996802   975M  5 Extended
/dev/sdc5       232443904 234440703   1996800   975M 82 Linux swap / Solaris

Some additional info:
I added --exclude=/srv to my fsarchiver settings, and the result is the backup you see that's only 3G. So clearly without that exclusion it's backing stuff up from another disk, because the only other folders under /srv are "pillar", "salt" and "ftp", all of which are tiny or empty.

thank you! I'll just leave the exclusion in place and call it resolved.