A couple of months ago I started up a micro instance of "Microsoft Windows Server 2012 RTM with SQL Server Express" AMI. I checked to see I could see the default page in IIS. And that was it. Then I forgot about it for 2 months.

When I check back I see that I've been charged about $50 each month for it. I can see that the CPU utilization has hovered around 60%, periodically spiking to 100%.

Could anybody explain to me the reason for this usage? I have ubuntu instances which have actual sites on them but their cost is nowhere near this (also micro instances).

My first thought is that it is doing windows updates. But from the CloudWatch monitor I can see that only CPU and data in is doing much of anything. There is no disk reading/writing at all.

Any light shed on this or how I might mitigate this usage would be appreciated.


Amazon charges you for every hour an instance is running, even if it's doing nothing. It's taking up resources - RAM, disk space, CPU reservations, etc. - whether the CPU is at 0% or 100%.

If it has Provisioned IOPS EBS volumes, they cost even with no I/O.

Basically, check your AWS billing reports. The charges will all be outlined there, in great detail.

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  • Thanks. I had not appreciated this - That they cost even when doing nothing! The previous boxes I mentioned seemed to cost barely anything so I assumed that they only costed for the time spent when they were serving requests. Which now sounds silly... – ben Mar 10 '14 at 9:01

Well, first - you are charged by working hour, IIRC.


so CPU is irrelevant. Letting it running for a month due to carelessness means pay for it. Mitigating this is simple - take responsibility for the VM's you are starting.

Second - you have to tell us. As in: this is something to analyze. It is definitely not normal. I manage a lot of VM's - some of the mwith various SQL Servers on them - and one show a high CPU usage without actually being used. COuld be a driver issue. You have to at least do baseline adminsitration and figure out which process used the time to make a sensible answer possible. It may be your box - due to bad patching - is now part of a botnet.

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Well, there are a few potential culprits for the high CPU usage, namely IIS and SQL Server; that said, I'd actually investigate it. Run a perfmon trace for a few hours/days, then take a look at which processes are actually consuming resources.

You can guess all day, but hard data will win every time. As previously mentioned - this does have nothing to do with the cost of the instance, which is pegged to time running, not resources used.

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