Rackspace (RAX) is finally putting the final nail in the coffin of its Slicehost-based cloud servers, and through 2015, it will help customers still hanging onto the aging first-generation cloud migrate to its OpenStack-based infrastructure-as-a-service (IaaS) offering.

This month, the first of many customers will get a notice from Rackspace about migration from the old cloud to the new(er) cloud. Rackspace plans to give customers 30 days of warning as to when their servers will come up for migration.

Shifting to a more modern cloud is good news, anyway, even though some customers are likely hooked on the technology they already know. But the even better news is that customers aren’t necessarily going to be on their own to make the transition. According to a snippet from a customer letter posted on Gigaom, “If you choose not to self-migrate, Rackspace will migrate your First Generation servers on your behalf at the end of the self-migration window.”

Click here for Talkin’ Cloud’s Top 100 CSP list

Slicehost was Rackspace’s early attempt to compete with the burgeoning Amazon Web Services (AWS). Rackspace purchased Slicehost back in 2008. That was long before Rackspace got involved with NASA in developing OpenStack, which has been growing in popularity as an open source cloud software solution.

But as for Slicehost, its days have been numbered for some time. Back in 2011, Talkin’ Cloud reported that Rackspace was migrating Slicehost customers to its OpenStack-based cloud. Now, it seems the holdouts are out of time and will be migrated off of Slicehost this year.