As recent sparring between NetApp and Sun proves, such blurred lines can often cause tenuous relations to turn ugly quickly. Ugly and unclear, I should add, because I don't think anybody truly understands what the two companies are arguing about and why. And like two children caught fighting, both are claiming the other started it, adding that much more uncertainty to the dispute.

If you haven't followed this latest example of what many -- including the litigants, when speaking of the opponent, of course -- see as frivolous lawsuits, lucky you. I'd also like to add that you haven't missed much, because little has been said by either party.

The war is being fought not only in court but also in the blogosphere. In his blog, NetApp founder Dave Hitz quotes a ZFS (Zettabyte File System) suffered an acute case of flattery/imitation with WAFL (Write Anywhere File Layout), the file system that rules in NetApp land.

Sun CEO and president Jonathan Schwartz counters on his blog that NetApp has been after StorageTek patents for some time, and that once Sun acquired StorageTek, NetApp decided to sue Sun rather than negotiate licensing.

A more obvious contradiction between the two parties is Hitz's statement that Sun lawyers made the first move by requesting NetApp to settle alleged patent violations. Schwartz has denied Sun ever made such a request.

Where does this lead us? Probably nowhere, given that we are all aware that "patent infringement" has become an empty phrase that signifies little outside the court.

Not persuaded? Consider the odds that two well-trained engineers or engineering teams could come up with a very similar solution to the same problem independently. Those odds are darn high, if you ask me.

If we could compare the inner workings of every proprietary solution on the market today, we would find many striking similarities. Are those similarities intentional appropriations of another's ideas? Probably not. But you can see how the temptation to use the court to muscle an opponent out of the market is too hard for some to resist.

Whether or not this is indeed the reasoning behind their current litigiousness, NetApp and Sun have been on a collision course for some time.

According to IDC, NetApp led the pack of single-digit market share vendors in 2006 networked storage revenue, a group that follows the three big vendors, EMC, HP, and IBM.

However, the gap between NetApp and its single-digit competition has been narrowing for the past few years. In NAS system revenue, NetApp remains second, right behind EMC, with Sun a distant also-ran. But if you look at the tumultuous SAN space, the rivalry becomes palpable, with Sun nearly doubling NetApp's take, although both are far behind the front-runners.

These market positions set the stage. Sun could hit NetApp sales where it hurts the most both with ZFS and its recent partnership with Microsoft, an alliance that reminds me of the fall of the Berlin Wall.

For example, the truce between Sun and Microsoft could also land Windows Storage Server on some powerful gear, a combination capable of becoming the fiercest rival to NetApp's unified storage vision.

Another point of friction, and not only with NetApp, is Sun's recently announced intention to acquire Cluster File Systems (CFS), which will give the vendor a preferential seat over future developments of Lustre, the powerful and venerable parallel file system.

Recent conversations with Panasas, a parallel storage cluster vendor, suggest that Sun's acquisition of CFS is at best perplexing, given the company's involvement with pNFS (parallel NFS), a project that includes Panasas and NetApp.

Once again, it seems that customers and competitors alike are left wondering which Sun they will face tomorrow.

With litigation looming, I forecast possible storms to come.

Join me on The Storage Network with questions or comments.

Mario Apicella is senior analyst of the InfoWorld Test Center.