Symantec Web Gateway proxy component cache over the 93GB limit is filling up the disk, making the system unavailable.
Rogue machine bombarded appliance with large amount of junk traffic causing the cache log to grow to 93GB before rolling over to 16GB.
This rapid log growth filled the disk, causing the system to become unresponsive.
Some proxy traffic that is filtered by ACL rules for which there is no response may result in a large amount of log entries in cache.
Persistent client request traffic may be generated by one machine.