Servers with many accounts and a large /home directory may take too long to finish backups with Jetbackup.
[11:50:24 root@myserver ~]cPs# df -hP
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-home 5.1T 2.2T 2.9T 43% /home
One reason for the slowness might be that the default resource limits set by Jetbackup for your server are too low.
Increase the maximum resource limits like CPU, disk, and process priority(nice value) that Jetbackup can use in "WHM / Jetbackup / Settings / Resource" tab. IO and CPU Limit settings are only available on CloudLinux servers.
You can find more details about the settings in Jetbackup 4's legacy documentation:
The Resource tab is called 'Performance' in Jetbackup5: