Low disk space on the disk drive or drives hosting an ArcGIS Server site's installation or log directories affects performance and impedes some site operations. Beginning in 10.6, ArcGIS Serverthus continually monitors remaining disk space on these drives, and will log messages when either drive is near full.
Monitoring is done for both single-machine and multi-machine server sites. For multi-machine sites, disk space is monitored for each machine in the site.
If the drive hosting an ArcGIS Server installation directory or log directory has less than 10GB of usable space remaining, a message will be logged every hour:
The ArcGIS Server machine <machine_name> is running out of disk space on <path_name>. Increase disk space on this machine.
If available space remaining on a drive is between 1 and 10 GB, a WARNING level message is logged; if free space is less than 1 GB, a SEVERE level message is logged.