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I requested an Amazon EC2 instance and sometimes it hangs. What could be the possible reasons for the server to hang? Is there something that can be done or detect before it hangs? Are there any good opensource monitoring tools which could detect this and take a preventive measure.

How system administrators deal with this issue?

Thank you Bala

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You've tagged this Linux and Server-2003. Which one is it? – Mark Henderson Mar 9 '10 at 23:33
Its actually linux. – Boolean Mar 9 '10 at 23:42

Do you mean it hangs on request, not sometime later?

There are two options. One is that Amazon's call is just failing - I've seen stats that claim around 2% of all Amazon API requests fail for "no good reason" and you should always have a retry-on-fail kind of thing coded up.

The other is that you're doing something clever when your instance is starting and that's causing the actual linux OS to hang during its boot cycle. Like having added an init script to go insert some dynamic DNS or whatnot, or anything else relying on an external dependency that causes it to freak out. I'd move any custom stuff late in the boot process and maybe get some remote syslogging to see if there's something really going wrong at the OS level.

I'd tend to put my money on the former, however.

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I've seen similar issues (I think it's a little higher than 2%, I'd guestimate its more like 10% but that's not at all scientific). You definitly can't just assume that because you stick in a request, amazon will just work. – Jim B Mar 10 '10 at 2:30

Following on from Ernest's answer, you can usually get a clue as to what's happening by checking the console output from the instance startup. This is available as a link if you start your instance via the AWS Management Console, or alternately by using the ec2-get-console-output command from the EC2 command line tools.

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