Watch those permissions
By Rick Cook
Although we usually think of "security" in storage as meaning not losing data, it's important to realize that storage systems face risks from malicious tampering or data theft as well. This is especially true of network-attached storage (NAS) where server and storage are combined and hooked onto the network.
The major concern for storage administrators is to make sure that the appropriate permission levels are set to allow only authorized users access to the data on the NAS server. Although many modern NAS servers can be brought up in a matter of minutes, it can take a lot longer to set the appropriate permissions for users to access the data. There is a related problem in a heterogeneous environment where the same server may be supplying data to both Unix and Windows NT systems. Unix and NT use significantly different methods of controlling access to files.
Unix NFS security is based on a distributed model, where, broadly speaking, each machine on the network is responsible for maintaining its own security. NT uses a more centralized approach with a single Primary Domain Controller (PDC) managing permissions for the entire domain via access control lists (ACLs). There needs to be some method of translating between the different kinds of permissions if Unix users are to be allowed to access NT files--and vice-versa--safely. In NAS servers that support heterogeneous access, the translation is almost always done by the server's operating system.
Procom Technology Inc. has a more detailed explanation of NT and Unix permissions and how they differ, as well as a discussion of how the company's NetForce NAS server handles the problem, at: http://www.procom.com/homepage/products/nfds.asp.
About the author: Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.