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No one likes a heart-stopping AWS bill shock so now there's a machine learning tool to help detect cost anomalies

(2020/09/28)


AWS has introduced [1]Cost Anomaly Detection , a new feature now in beta driven by machine learning that pledges to notify admins of "unexpected or unusual spend".

Bill shock is a problem suffered, on occasion, by small and big AWS customers alike. At the small end, there are cases like that of Chris Short, using AWS for his Content Delivery Network (CDN) to scale his website at a cost of around $23.00 per month. One morning he [2]woke up to a bill of $2,657.68, thanks to sharing a 13.7GB file that proved unexpectedly popular. At the other end, the average organisation is over budget for cloud spend by an average of 23 per cent, as we reported [3]here .

While puzzling out what specific cloud services will cost can be a challenge, the big cloud providers are pretty good at showing you where your money has gone with them individually. AWS has a Cost Management service which includes reports, budgets and recommendations, to which the company is now adding Cost Anomaly Detection.

[4]

Creating a Cost Monitor for AWS Anomaly Detection

This is configured by adding a Cost Monitor to an AWS account. There are four types of monitor. The generic AWS Services monitor is fully automated. The Linked Account monitor is specific to other AWS accounts linked to an organisation. A Cost Category monitor evaluates spend for a specific category as labelled by the administrator. Finally, a similar Cost Allocation Tag monitor evaluates spend for services with a specific cost tag.

Why cloud costs get out of control: Too much lift and shift, and pricing that is 'screwy and broken' [5]READ MORE

Once the type of Cost Monitor is selected, admins set an alert threshold, which is the minimum size of an anomaly that will be notified, the frequency of alerts from as they arise to daily or weekly, and a Simple Notification Service (SNS) through which the alerts are sent. Daily or weekly summaries are sent by email to up to 10 recipients, but admins who opt for individual summaries must go through SNS. This is inexpensive and the first 1,000 emails, or 100 SMS messages, per month are free. Each AWS account can create one AWS Service monitor and up to 101 additional cost monitors.

How good is the anomaly detection? That is the key question and one only customers will be able to answer. The detection engine runs around three times a day and after billing data is processed, which means there is some (potentially expensive) delay. It is driven by a machine learning model, indicating scope for both under and over-reporting, but the service is expected to improve as the model is refined.

People may wonder whether it is really in the interests of AWS to provide a service that helps customers spend less money. It is true that, like every company, the cloud providers are always trying to persuade their users to adopt new services or add premium features. That said, none of the experts we have spoken to think that there is deliberate confusion marketing – where pricing is deliberately complex so that customers spend more than they intend – or that providers like having their users waste money. The counter argument holds more sway, that the providers want satisfied customers. The current high demand for cloud services makes this position an easy one to hold.

Anomaly detection is not the complete answer to overpaying. After all, if an organisation paid more than it needed to last month, it is not an anomaly if it does so again. ®

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[1] https://aws.amazon.com/about-aws/whats-new/2020/09/introducing-aws-cost-anomaly-detection-preview/#:~:text=AWS%20Cost%20Anomaly%20Detection%20is,increases)%20with%20minimal%20user%20intervention.

[2] https://chrisshort.net/the-aws-bill-heard-around-the-world/

[3] https://www.theregister.com/2020/09/03/cloud_control_costs/

[4] https://regmedia.co.uk/2020/09/28/createmonitor.png

[5] https://www.theregister.com/2020/09/03/cloud_control_costs/

[6] https://whitepapers.theregister.com/

AWS is nothing.

Anonymous Coward

DataDog are the worst for this. Their salespeople are like stereotypes of 80s user car salesmen.

Anonymous Coward

This is a good thing.

We once had that with a telecoms provider. We had setup an ISDN link between 2 data centres - it was only ever a backup link. All was going well but one Sysadmin has setup an app on DC1 that unexpectedly pinged DC2 over the ISDN link causing it to activate the ISDN call. This went into a billing black hole for months - we never saw the daily/weekly/monthly ISDN usage until the book (lots of invoice pages showing the call initiation) arrived to my cost centre to be paid. It was a lot of cash... I ended up negotiating with the provider to drop most of the charge and removed the offending server.

Why Not?

I do wonder how many organisations chasing cost savings by moving to the cloud will find themselves seriously reamed over the next decade. Users are very good at ramping up usage accidentally. Anyone who has seen an email storm with thousands of "remove me from the list" replies will understand that, now make that "pay per byte" and watch the CTO & CFO wince.

I feel little sympathy for them.

"the average organisation is over budget for cloud spend by an average of 23 per cent"

RM Myers

Ah, this explains all the cost estimates where organizations find that they can save 20% if they just move to the cloud.

Absentee, n.:
A person with an income who has had the forethought to remove
himself from the sphere of exaction.
-- Ambrose Bierce, "The Devil's Dictionary"