We were seeing webmail outages up to 5 minutes at a time on the Safari server yesterday, increasing in frequency throughout the day. The decision was made to move the Apache includes to the SSD array currently housing MySQL, to speed up config reloads. For us that means moving the DA user data. This is proving to take longer than predicted, there's a strange blocker to determining progress other than "done" or "not done."
Giving an ETA for DirectAdmin to be back online would be irresponsible. Best course of action is see this through. No email access or delivery is harmed by this. This is only administration control panel access.