The costs for supporting open source storage software show up in different ways. Open source vendors are in general agreement that managing open source code and changes to it require, as a rule of thumb, administrators with at least two to four years of experience.

"Users who like the idea of modifying open source code need to take a close look at the code to make certain that they can work with it and that it is within their skill set to modify," Cambridge Computer's Farmer says.

Integrators like Terry Hull of the Network Resource Group (NRG) also encounter other issues with product support.

"Getting to the root of a problem when you have open source layer upon open source layer is rarely easy and the thing we (NRG) know we are giving up with open source storage software is a significant margin of management," Hull says.

Another major concern for open systems storage software is the depth of product functionality. Open source products like Amanda and OpenSMS, a policy-driven systems management storage software product, almost always have certain product restrictions. For example, Amanda will not backup Microsoft Windows hosts unless SAMBA, a file and print sharing utility, is first installed on the Windows host, and Amanda offers no media server option so all backups must go through a central server. OpenSMS only officially supports Linux 2.4 and 2.6 running on an XFS file system though it suggests it should work on other UNIX platforms and, with some porting, on JFS file systems. OpenSMS offers no integration with Microsoft Windows platforms.