Two years ago, with its oil exploration and production data doubling every 18 months, TotalFinaElf E&P USA Inc. considered building a storage-area network (SAN). It had more than 18TB of shared data directly attached to more than 50 servers at its Houston headquarters, and it wanted to make it centrally accessible and easy to manage.
But executives decided that a SAN would be too inflexible for the company's needs and instead chose a considerably less expensive network-attached storage (NAS) system, the latest upgrade of which was completed last month.
"NAS is less complex than a SAN, especially in a heterogeneous multiaccess, multifile system environment such as ours," says Fred Webster, manager of IT at the U.S. arm of France's TotalFinaElf SA, the world's fifth-largest oil company. "While some SAN solutions might be configured to deliver greater throughput for a given scenario, it would be at the cost of less flexibility and greater complexity."
A Better Consolidator
Webster isn't alone in his thinking. At a time when about 20 percent of the Fortune 500 companies have installed SANs, NAS is more than holding its own as a server consolidation technology that makes storage management easier, analysts say.
"I don't think SAN is an architecture that consolidates storage," says Pushan Rinnen, an analyst at Stamford, Conn.-based Gartner Inc. SANs are still built mostly from homogeneous islands, and each vendor is selling its own Fibre Channel disk arrays, he says. "But with NAS, you can serve Unix or Windows platforms, client or server storage. So from that point of view, NAS is ahead of SAN," Rinnen says.
And from a management point of view, the simplicity of NAS has always been preferable to SANs, he says.
TotalFinaElf's Design
TotalFinaElf spent $3.2 million to construct its NAS system, which includes two NetApp 760 and four F880c filers from Sunnyvale, Calif.-based Network Appliance Inc.
With the exception of its AS/400 data, TotalFinaElf stores all its data on NAS devices. Some 90 high-end Unix workstations also access data on the NAS filers by way of the Network File System (NFS) protocol.
The NAS filers also offload the NFS-based file sharing from TotalFinaElf's Solaris servers, allowing four of those machines to be used for other applications.
Another payoff: By moving from direct-attached storage to NAS, TotalFinaElf has reduced its staff from several file administrators to one part-time technical systems administrator -- something that wouldn't have been possible with a SAN, Webster says.
The NAS devices also run the Common Internet File System (CIFS) protocol to allow 37 Windows NT servers and about 450 desktops running Windows to access data. But Webster says he ran into integration challenges in trying to support both Unix and Windows.
"We don't commonly allow Unix systems to natively share the same logical NetApp filer drive as PC systems do because the Unix permissions and the Microsoft [access control lists] get in the way of each other," Webster says. "You really have to think about it for your filer implementations."
His team also spent about four months working out integration bugs with the backup system. The problems were resolved when Legato Systems Inc. in Mountain View, Calif., released Version 6.1 of its Enterprise Backup and Restore management software.
"That was a big issue because when we did have to go back to tape, my NT administrators had to rebuild access control lists for a while," Webster says.
TotalFinaElf also faced a dramatic increase in the time required to complete its weekly tape backups. Using NFS, the system required some 60 hours to copy 18TB over Gigabit Ethernet to the tape subsystem.
Webster worked with Legato and Louisville, Colo.-based Storage Technology Corp. to implement a system running the more efficient Network Data Management Protocol (NDMP), which automatically finds linear tape-open drives in the tape library and directly connects them via SCSI to the NetApp filers. By separating the data path from the control path, the NDMP protocol minimized demands on the network. "It reduced our backup window by 66 percent. Now we're down to 20 hours," Webster says.
However, he adds that he would like to be able to scan for viruses on his CIFS and NFS volumes. "PC users are notorious for finding ways to disable client-resident virus scanning, so it's a stretch to depend solely on the client for this service," Webster says. "We understand, however, that there are performance and administration issues if virus scanning is placed on the filer."
Webster says IT managers considering NAS should make sure they understand the architectural concepts and components involved. "Look at your needs" and make sure NAS correlates with that, he says.
TotalFinaElf's Case for NAS
The world's fifth-largest oil firm cites four reasons why it choose NAS over SAN technologyBenefits- Workstations and server applications have shared access to both Windows and Unix file types.
- NAS consolidated storage more efficiently than SAN alternatives.
- The cost of deployment was substantially less than that of comparable SAN designs.
- Fewer employees are required to manage NAS devices.