looking at the logs on cdsfs0 over the past week, here are the number of times an error is reported which could have lead to /ligo being unavailable for a short period of time:

Wed Nov 30 04:43
Wed Nov 30 05:51
Wed Nov 30 18:37
Wed Nov 30 20:50
Fri Dec 2 04:40
Mon Dec 5 03:48
Mon Dec 5 14:52
Mon Dec 5 16:17
Mon Dec 5 17:32
Mon Dec 5 19:15
Tue Dec 6 10:42