Depending on our customer needs, different file service options are available. Some customers need access only from NT, others only from UNIX, others need to access their files from both. We feel that eventually all customers will need access from both; even UNIX-only users will want to share data with NT-only users.
NT clients access file servers using the Common Internet File System (CIFS) protocol [Leach] (which is Microsoft's new name for the Server Message Block (SMB) file protocol [SMB].) UNIX clients use the Network File System (NFS) [Stern] protocol. Some file servers support one or both of these protocols. File servers come in all sizes from small to extremely large. We feel at this time the file service marketplace can be summarized as in Figure 1.
For small-scale NT file service, NT Server is appropriate. A UNIX Server is appropriate for small-scale NFS service. If the data must be accessed by both, a UNIX server running SAMBA [SAMBA] or Syntax TotalNET [TAS] is fine. We have multiple terabytes of data and it almost always needs to be accessed from both kinds of clients. Therefore those solutions have been nearly phased out in the past year.
For medium-scale file service with CIFS and NFS we choose Network Appliance Filer (referred to as the NetApp Filer) [Hitz1] dedicated file servers. A typical user has a directory on a NetApp Filer that is exported via NFS for access from UNIX and as a ``share'' available to NT systems. Some customers have requested to have the share only be a portion of their directory structure, usually a sub-directory called ``PC''. We get this request less often now. We are very happy with the NetApp Filers' ability to solve the problem of integrating NT and UNIX. On top of that we get snapshots, RAID and other features. Performance is exceptional for NFS as well as CIFS, almost dispelling the general perception that CIFS's design prevents fast implementations from existing.
Management of the NetApps is ``free'' since they access NIS for UNIX account data and NT Domain for NT account data. By keeping user names in sync, these systems require very little new administration tasks. The NetApp ``does the right thing.''
While the NetApp Filers are not inexpensive, we find their total cost of ownership is on par with other solutions. We occasionally price out an equivalent PC-based server for comparison and generally find the price per megabyte comparable after including RAID and other features. Such a system would not integrate NFS and CIFS as well, nor would performance be as good. Also, with our UNIX background, we find the Network Appliance File Servers easier to manage.
Our UNIX NIS configuration is automated and includes home spun components that update our NetApps (see [Limoncelli] for complete details). In fact, since the updates are automated as part of our NIS push system, additional NetApps require nearly zero additional work once it is included in our NIS database of NetApps. We encourage each large (200-400) group of customers to procure its own NetApp Filer which we then manage.
Because each small group of customers procures its own NetApp Filer, we have not had to evaluate solutions for large amounts of data. We have a large amount of data, but we have developed ways to manage it efficiently as many medium chunks of data.
