We put that question to the big three UNIX/Linux vendors -- IBM, Hewlett Packard (HP) and Sun -- to understand how they help their customers decide where, when and if a migration makes sense.
"Typically where the customers' head is at, is he doesn't want to change anything unless he has to, said IBM's Karl Freund, vice president of pServer Product Marketing.
All three of the vendors clearly recognize customers are looking at Linux though they do not actively solicit their own UNIX customers for migration to Linux. HP's Worldwide Linux Marketing Manager Daniel Gilfix said HP doesn't solicit its own customers because the workloads where UNIX offerings are usually deployed are not the typical proven and tested Linux sweet spots.
These sweet spots occur in different places, but, in particular, edge-of-network application workloads are the ones offering a lower TCO and better price-for-performance running on Linux.
"Edge of network type applications, those are workloads that have proven themselves quite well on Linux," said Freund. "That's where the migrations tend to occur."
Workload considerations are key when looking at a potential migration both in terms of the platform and timing, said Gilfix.
"Migrations often are driven by timing, such as when a workload matures and/or is proven more efficient on another platform, or when business demands dictate," he said. "The most successful migrations are those in which the customer takes the initiative proactively as opposed to being forced to move urgently."
Gilfix said timing depends largely on a customer's comfort level with his or her questions that should be asked about their current reality:
Also UNIX, in the eyes of the big vendors at least, remains ahead of Linux in terms of features and functionally.
"Quite often, the right choice has very little to do with features and functionality since most operating systems built around the POSIX specifications offer a solid foundation," said Sun's Chris Ratcliffe, group manager for Solaris Marketing.
Ultimately, the major UNIX vendors don't see Linux as something that will entirely replace UNIX. Both UNIX and Linux have their place depending on an analysis of workloads taken in the context of price vs. performance.
While UNIX is positioned to remain at the high end of features, scalability performance for mission critical applications, on the other hand, Linux is positioned by the big dual UNIX/Linux vendors as being more for non-mission critical edge of network applications. In the final analysis, it may very well boil down to a price issue.
"Migration from UNIX typically is only going to happen when a company says 'I just want off of UNIX because I have more choice of vendors and lower hardware price points if I go to a Linux platform'," said IBM's Freund.