Roundcube's Disk Usage page shows inaccurate cPanel Account values for systems with multiple partitions

Symptoms

When viewing the Disk Usage within Roundcube, the cPanel Account usage shows an inaccurate number on systems with more than one partition.

Description

This issue is caused by only the first partition's usage being reported within Roundcube:

[root@server ~]# quota -u cptesting
Disk quotas for user cptesting (uid 1004): 
Filesystem blocks quota limit grace files quota limit grace
/dev/vda2 664 11520000 11520000 355 0 0 
/dev/vdb 528240 11520000 11520000 9768 0 0 

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-47222. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

Disk Usage for an email account can be viewed within the Webmail Home portal:

The Webmail Interface