On 3/29/11, mcclnx mcc <mcclnx at yahoo.com.tw> wrote: > I don't think it is cable problem. The reason are: > > 1. it happen every 3 to 4 weeks once. > > 2. problem last 4 to 5 hours then back to normal. > > 3. not one server has this problem, several servers on that rack all have > problem at same time. Did you note down the exact dates and times of the past few occurrences? Have you checked crontab to see if anything is scheduled to run during those times, e.g. monthly backup set for the wrong time such as 2pm instead of 2am.