website stops responding
Posted by netedgetech, 04-21-2009, 07:16 AM Hi, I have 3 servers ServerA(Web, mail), ServerB(MySQL+Master replication), ServerC(Mysqlslave+web) It happens that my website stops responding for few mins and then it comes back again automatically. I checked the server logs but I couldn't find any suspicious. Also, while the website is not accessible when I try to connect internally from ServerC to ServerA or ServerB using SSH. It takes lots of time (approx more than 60 seconds) to connect. When website starts working SSH is also working fine. This is very complicated for me. Can anyone let me know what should be the problem or how can I find root cause of this problem?
Posted by jseymour, 04-21-2009, 07:34 AM Check your server load during the down time. Sounds like something is using all your resources. Try top.
Posted by tulix, 04-21-2009, 09:57 PM Check you HDs. HD's errors will cause OS hang ups. Do you have this problem with all the servers or just one? One way or another it probably will be disk I/O problem. Try to run (if it is RedHat derivative) yum -y install sysstat and then iostat -x 6 and look at the last column - what is % of utilization during let say 1 minute.
Posted by UNIXy, 04-21-2009, 10:14 PM As others have mentioned, get some historical data on your server. This way if you're not at your desk you'll be able to go back and investigate. There's the data collector SAR. Here's a post on how to use it: http://www.webhostingtalk.com/showthread.php?t=729846 Good luck