Google App Engine, Tumblr and Dropbox worked on ensuring the availability of their cloud-based services Monday after each suffered outages for several hours Friday.

Google said App Engine, its platform for developing and hosting web applications in Google-managed data centers, went down from 7:30 a.m. PST to 11:30. a.m., PST, as it experienced slowness and errors. As a result, 50 percent of requests to the App Engine failed.

[Related: Analyst: AWS Could Lose Customers If Outages Continue ]

"We apologize for this outage, and in particular for its duration and severity," Google said in an unsigned post on the company's Enterprise Blog. "We know that hundreds of thousands of developers rely on App Engine to provide a stable, scalable infrastructure for their applications, and we will continue to improve our systems and processes to live up to this expectation."

The company said no application data was lost and application behavior was restored. Google said it would issue credits to customers for 10 percent of their usage in November.

Google said it is bolstering its network service to guard against traffic latency.

"In response to this incident, we have increased our traffic-routing capacity and adjusted our configuration to reduce the possibility of another cascading failure," Google said. "Multiple projects have been in progress to allow us to further scale our traffic routers, reducing the likelihood of cascading failures in the future."

The microblogging platform and social networking website Tumblr said service had been restored by 11:14 a.m. Friday and promised it will issue a full report. The company could not be reached for comment Monday.

Dropbox on Friday morning displayed a message that said, "Error: Something went wrong. Don't worry, your files are still safe and the Dropboxers have been notified."

Dropbox could not be reached for comment Monday.

There seemed to be no definite relationship among the three outages, with one analyst saying the disruptions show the cloud is still not completely stable.

"This shows the cloud industry still has work to do to improve on overall availability and performance," said Jeff Kaplan, managing director of Thinkstrategies. "There are inevitably going to be disruptions to service availability, and it's key for service providers to minimize these occurrences and for cloud consumers to mitigate their risk by having a backup and recovery plan in place and by exploring ways to take advantage of offline service options."

PUBLISHED OCT. 29, 2012