Amazon Web Services customers this week are worrying about a server reboot the provider is pushing out, but if users have architected their applications properly, they shouldn't be concerned, experts said.
AWS customers have been receiving emails from Amazon informing them that the servers they are using will be rebooted "in order to receive some patch updates," according to one letter Randy Bias, CTO of Cloudscaling, posted online. That has left some users scrambling to make sure their applications won't go down during the reboot.
"Today is apparently EC2-reboot-Wednesday. Also known as the day some CIOs learn that (1) they use EC2 and (2) they're not using it very well," William Vambenepe, a software architect at Oracle, wrote on Twitter. EC2 stands for Elastic Compute Cloud and is AWS' compute offering.
But other experts, as well as Amazon, reminded users that the reboot isn't anything new or unique to cloud services. "This rollout schedule matches pretty closely with the maintenance schedule you might see from traditional hosting providers or internal IT groups when they roll out software patches or updates," Kay Kinton, an Amazon spokeswoman, said.
GoGrid, an infrastructure-as-a-service provider, also noted that if businesses run their own servers internally, they have to make similar updates. Moving to the cloud saves administrators a lot of management trouble overall, but this kind of required reboot might be "trouble some thought they left behind when they got to the cloud," Jayson Vantuyl, chief engineer at GoGrid, said.
Users who have architected their systems to include redundancies shouldn't have a problem, he said. "If you don't have redundancy, you're in the situation you already were," he said. By that he means that Amazon -- or any other cloud provider -- doesn't guarantee that hardware isn't going to break. If a user doesn't have redundancy built into their application and a piece of hardware becomes unavailable for any reason, their application will be impacted.
Amazon is giving users notice of when their applications will be impacted so they have the option to handle the reboot on their own. Netflix, which runs its streaming video service on AWS, opted to reboot on its own schedule, Adrian Cockcroft, director of cloud systems architecture for Netflix, wrote on Twitter.
Doing so allows users to ensure that at no time does their entire cluster go offline, said Mark Worsey, GoGrid's CIO. "They can do it methodically," he said. "It allows a company to do this in a controlled manner so they avoid the big massive single reboot that creates an outage," he said.
Also, Amazon is handling the updates zone by zone. "We are careful not to perform updates to multiple Availability Zones in the same region on the same day so that customers won't have instances in different Availability Zones update on the same day," Kinton said. That means a customer who has architected for failover into another region won't be impacted by the reboot.
