The RAM consumption has been increasing gradually since the last appliance reboot, being now very high.
PAM 4.2.1
There is an issue with RAM consumed by hung xcd_upd processes that can make a progressive RAM increase.
Apply published patches 4.2.1.10 and 4.2.1.19.
These patches are included in PAM 4.2.3+, see the entries for DE633768 and DE637971 on documentation page: Resolved Issues in 4.2.3