For example, bugs were recently discovered in the underlying Xen hypervisor used by AWS, and some AWS machines had to be rebooted as part of the patching process. Also, the physical servers that do the work on the backend can, and do, fail. Without automatic safeguards built in, websites built on AWS can behave unexpectedly or even become unavailable when servers crash or reboot on the backend.
In general, you should ensure important sites can run from more than one availability zone (AZ) within a region. Typically, this entails having the database backend set up for multi-AZ deployment from the get-go. Similar to how having more than one database server in an on-premises deployment is more expensive, expect to pay more when you choose a multi-AZ database option.
The most typical setup entails setting up an Elastic Load Balancer (ELB) to distribute incoming application traffic across multiple compute instances. Traffic can be automatically diverted from unhealthy instances to healthy ones, which could span across multiple AZs in the event of a catastrophic failure of a particular AZ.
Don't forget security
AWS takes security seriously, which is no surprise considering you can set up literally hundreds of production servers or tear them down with the click of a mouse. For example, at least one promising start-up was wiped away after a hacker broke into its Amazon EC2 control panel and basically erased the entire infrastructure.
To better manage security, AWS recommends setting up users with limited permissions to manage the resources under their charge, as opposed to a "root" user with unlimited access. Just like in a typical Linux system, users can be allocated to groups, while additional roles can be created and assigned to users or groups.
In addition, AWS also offers multifactor authentication (MFA), which is available as in both hardware and virtual options. For hardware MFA, AWS supports security fobs manufactured by Gemalto, a third-party provider. Alternatively, a virtual MFA app is supported, with Google Authenticator supported as an option on Android, iPhone and BlackBerry, and an AWS Virtual MFA app on Android.
Monitoring your cost
Finally, the aspect of cloud computing that you probably hear about the most is its capability to reduce infrastructure cost. As businesses are slowly finding out, however, the corresponding increase in operational costs can in certain circumstances exceed the cost of an on-premises deployment in relatively short order.
To help users gain greater insights into the cost of their cloud deployments, AWS devised a monthly calculator where users can compute the cost of their deployments based on the services that they use, according to their estimated disk and network usage levels. This can help businesses decide if they can do without certain levels of reliability or services.
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