Cloudera Co-founder Mike Olson is no longer the company's CEO, according to a Tuesday morning blog post from Olson. Former Arcsight CEO Tom Reilly is taking over the company's leadership role, while Olson is transitioning to a position as chief strategy officer and chairman of the board.

Here's Olson's explanation from his post:

We're building a company that we expect to stay independent and to lead the market for many years to come. That will demand relentless focus on operational excellence and on the technology and solutions that our customers need. The combination is, at our present scale, two jobs, not one.

Tom led Arcsight through its IPO to industry leadership in mission-critical, bet-the-business security. He knows the enterprise. He's a been-there, done-that executive. He's run very successful enterprise software companies at global scale.

Tom's appointment as CEO allows me to concentrate my time with key constituents: Our product and engineering teams, our partners, our sales force, our customer-facing technical teams and – most importantly – our customers themselves. He and I have spent considerable time together over the last several months, building trust in both directions and planning for a smooth transition. Cloudera is a better company, today and for the long term, with the two of us working together.

It's kind of ironic that Olson is stepping down considering he was always considered the seasoned enterprise executive of a founding team custom built to grow into the company that Cloudera now is. It was the first company to make a living selling a commercial version of the Apache Hadoop big data platform, and it's still the biggest. Cloudera has raised $141 million in venture capital since launching in 2009, is doing about $100 million in annual revenue and has well more than 300 employees.

Before founding Cloudera along with Amr Awadallah, Jeff Hammerbacher and Christophe Bisciglia, Olson was CEO of Sleepycat Software. Sleepycat was the creator and primary developer of the BerkeleyDB database technology, and Oracle bought the company in 2006.