Some companies buy back stock. Sun has taken to buying back executives.

First it reprised CFO Michael Lehman. Now it's brought back Richard Green to run its software operation in the absence of John Loiacono, who went to pitch for Adobe a couple of months ago.

Green has been over at BEA co-founder Bill Coleman's software start-up Cassatt as executive VP of products, but before that he was VP and general manager of Solaris and used to lead Java development. In fact, he's advertised as having been instrumental in Sun getting that $1.6 billion settlement out of Microsoft to drop its Java antitrust suit and signing a so-called collaboration agreement with the Evil Empire. So he's right at home and it won't take Sun much to get him up to speed.

As Sun said in its announcement, "We could not have dreamed of a more qualified candidate."

Green will report to newly minted Sun CEO Jonathan Schwartz, who used to run Sun Software back when the world made slightly more sense.

Green's remit includes Solaris, the Java Enterprise System suites, the N1 management software, Sun Studio and the Java Studio development tools along with standards efforts and Sun's open source communities.

Green is only the latest high-ranking defector at Cassatt. The start-up has kissed four of its seven original founders good-bye and might have run out of money this summer were it not for a $15 million fourth round that it took in a few weeks ago.

Green has now been replaced by his former report, Rob Gingell, another one of the old Sun fraternity. Gingell, a Sun Fellow and erstwhile chief engineer, was CTO of Sun's software operation.

Now that he's back, Green will find the OpenSolaris scheme that was in the planning stages when he left realized. Sun has also adopted PostgreSQL, the open source database closest to its sometimes-friend Oracle, to distribute with Solaris, and has released the Solaris ZFS, its new 128-bit file system, to OpenSolaris. The company is now promising both technologies will be in the Solaris 10 6/06 commercial cut of the OS this June, the end of Sun's fiscal year. Computers should be able to boot from the thing by December.

The Zettabyte File System (ZFS) 1.0 is supposed to automate common admin tasks, protect data from corruption and provide virtually unlimited scalability. It eliminates the need for a (Veritas) volume manager. Sun describes ZFS, an industry first, as having a lifespan of 20-30 years. One wonders whether Sun will makes it that long.

(This is an abridged version of a story that appeared originally at www.clientservernews.com.)