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Amazon suffered another outage to its Elastic Compute Cloud service this week, after one of its data centers was struck by lightning. The disruption lasted about seven hours, during which time customers were directed to use alternate instances of the service.
Now, a lightning strike to a data center is a serious matter. But one of the key features of subscribing to a cloud computing model is supposedly its redundancy. If one part of the network goes down, it should be fairly simple to port services over to another portion of the network.
A bulletin was posted on the company’s “health dashboard”, which provides status reports on Amazon’s various cloud computing services, stating a loss of connectivity was filed at 6:39 p.m. on Wednesday, June 10. By 7:33 p.m., an update was posted stating a lightning storm caused damage to a single power distribution unit (PDU) in a single availability zone. “While most instances were unaffected, a set of racks does not currently have power, so the instances on those racks are down.” The bulletin goes on to say: “Users with affected instances can launch replacement instances in any of the US Region Availability Zones or wait until their instance(s) are restored.”
At 1:20 a.m. on June 11, Amazon posted a final bulletin stating that all instances had been restored.
It seems like the company did a good job of resolving the problem, communicating with customers, and offering an alternative solution to those affected. But this latest outage does little to alleviate one of the primary concerns businesses have about switching to the cloud – reliability. In a recent McKinsey & Company report on cloud computing it was noted that most internal IT shops are able to commit to service level agreements providing 99.99% uptime. Amazon, by comparison, promises 99.5% uptime for its Elastic Compute Cloud (EC2) service.
Clearly, work needs to be done on improving reliability if cloud computing is to achieve its promise.
In a cloud computing survey conducted by research firm IDC in the fall of 2008, performance and dependability were among the top three concerns of businesses thinking of switching to cloud computing services (security was the No. 1 concern). “Will critical instances in the cloud consistently be there when and as needed by the business?” analyst Frank Gens asked. “The complex web of interdependency that supports cloud services availability and performance . . . cries out for suppliers who can offer greater transparency of interdependencies as well as credible service level assurances.”
For the record, here is a summary of the findings of the IDC survey of 244 CIOs and businesses on the pros and cons of cloud computing.
Top Perceived Benefits of Cloud Computing:
1. Easy/fast to deploy
2. Pay for only what you use
3. Less in-house staff and lower costs.
Top Challenges of Cloud Computing:
1. Security
2. Performance
3. Reliability
4. Hard to integrate with in-house IT
5. Inability to customize
What Customers Want from Cloud Computing:
1. Competitive pricing
2. Performance assurances
3. Understanding of business and industry
4. Ability to move cloud offerings back to premises.
Source: IDC
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