NetApp F740

A fast, high-capacity multiprotocol file server

As your company grows, its data storage needs can also grow, requiring you to add file servers to meet the increased demand. And if your organization employs Windows NT and UNIX clients, you might need to replicate server assets for each client group. Before you know it, you have a room full of servers and a huge management workload.

One solution is to consolidate your NT and UNIX servers onto Network Appliance's NetApp F740, a dedicated multiprotocol file server with enormous storage capacity targeted at departmental file-service applications. The F740 is based on an Alpha processor and a proprietary OS called Data ONTAP that Network Appliance optimized for simultaneous file service to Windows and UNIX clients. The company claims that this single-purpose OS provides better scalability, reliability, and performance than a general-purpose OS such as NT.

Network Appliance designed the F740 hardware for speed, capacity, and reliability. The unit I tested in the Windows NT Magazine Lab had a 19" rack-mountable enclosure that contained a 400MHz Alpha processor, 512MB of Error-Correcting Code (ECC) RAM, 32MB of nonvolatile RAM (NVRAM) with redundant battery backup, a fibre channel interface for disk storage, a SCSI controller for tape backup, two redundant hot-swappable power supplies and cooling fans, an integrated 10/100Base-T network interface, and a quad 10/100Base-T interface in one of the six PCI slots.

A separate 19" rack-mountable fibre channel RAID storage shelf contained seven 18GB hot-swappable 10,000rpm hard disks (one was a hot spare) with fibre channel interfaces. The configuration I tested also included Common Internet File System (CIFS) and NFS licenses. You can add storage shelves containing 9GB or 18GB drives, up to a maximum capacity of 928GB. The disk subsystem employs RAID 4, but unlike with other RAID 4 implementations, the system writes data and parity bytes to a 32MB NVRAM cache in one operation rather than using the typical two-step parity disk write. Like the main enclosure, the storage subsystem features dual redundant fans and power supplies.

The heart of the F740 is its OS, Data ONTAP 5.3. The OS integrates transparently with NT domains and server-management tools. Because of the OS's compact size (it fits on two 3.5" disks), specialized design, integrated RAID support, and low overhead, Network Appliance claims the F740 provides better file-server performance than NT-based systems. My tests supported this claim.

To judge the F740's performance, I connected it to the Lab's 100Base-T benchmark network consisting of forty-two 350MHz AMD-K6-2-based desktop clients spread across three segments connected to a Cisco Systems' Catalyst 5000 switch. But when I installed the server on the test network, an OS bug prevented the F740 from authenticating with the PDC until I severed three of the four network connections to the server's 100Base-T quad card. After Network Appliance supplied an OS patch to fix the problem, server setup was quick and uneventful.

After plugging power cords into the F740's dual 115-volt power supplies, I connected the network to the server's integrated 10/100Base-T interface and turned on the system. A few moments later, the IP address that the Lab's DHCP server assigned to that network connection appeared on the F740's two-line LCD. I could then connect to the server through a networked client's Web browser and launch the setup wizard, which stepped me through a series of prompts for necessary information such as the server name, administrative passwords, the administrator's email address, IP addresses and subnet masks for the quad card's network connections, the DNS domain, and the presence of a WINS server. Setup took less time than I expected because Network Appliance delivers the disk subsystem preconfigured for RAID 4.

With the server running, I used Client/Server Solutions' Benchmark Factory FileBench file-server test to create a heavy file-service workload to see how the F740 would perform when handling several NT-based file servers—a reasonable scenario if you plan to consolidate existing file servers onto the F740. I constructed a test in which clients read a 64KB block of data from a 1GB file and wrote a 2KB block to a 1MB file. The test performs an equal number of reads and writes, and the benchmark agent on each physical client can simulate several virtual clients.

I ran the test with 15 to 150 virtual clients in 15-client increments. I set the think time—the time each virtual client waits before beginning the next read or write operation—to zero to maximize the workload on the F740. As a result, the workload represented a client population much larger than the 150 virtual clients I employed in the test. For comparison, I ran the same test sequence on a Gateway ALR 9200 server equipped with four 400MHz Pentium II Xeon processors with 1MB of L2 cache, 512MB of RAM, and five Seagate 10,000rpm hard disks using RAID 5.

I expected the F740 to provide fast performance under a heavy load, and it didn't disappoint me. The file server's peak workload of 553 transactions per second (tps) was more than three times that of the 4-way server's peak performance of 174tps. As you can see in Figure 1, the F740 also maintained its performance as the workload increased, performing approximately 481tps, or 87 percent of its peak workload, with the maximum 150 virtual clients. The 4-way server's performance dropped to approximately 128tps, or about 73 percent of its peak workload, at the 150-client level.

One benefit of Data ONTAP and its Write Anywhere File Layout (WAFL) file system is native support for CIFS, NFS, and HTTP file access protocols, which lets the F740 provide transparent file access to Windows and UNIX clients. In addition, the file system supports NT ACLs or UNIX-style file permissions, and you can automatically map NT users to their respective UNIX user accounts. Both features are particularly helpful in heterogeneous environments, letting you easily serve NT and UNIX clients from one system.

To test these features, I set up a scenario in which several users needed access to their files from NT-based PCs and Sun Microsystems workstations. I set up the necessary directories, files, users, groups, and permissions on the F740 just as I would on any NT-based server. I logged on as an administrator, used Windows Explorer to create the file and directory structure on the server, and used User Manager for Domains to set up users and groups. I then used Windows Explorer to assign server directory and file permissions.

Next, I installed a Sun Ultra 5 workstation on the network and used Solaris' Admintool to create two user accounts under usernames identical to those on the NT side. After I set up the Solaris accounts, UNIX account holders could perform only the operations their NT accounts permitted.

As the word appliance in the company's name might suggest, the F740 makes server-management tasks easy. Although you can manage the F740 from a terminal or PC connected directly to the server, Network Appliance provides a Web-based administration tool called FilerView that uses Java applets to let you perform management tasks from any PC on the network. One management convenience the F740 provides is its Snapshot system, which can take snapshots of the system at regular intervals (e.g., hourly, daily) depending on the needs of the user base. Like most third-party snapshot products, this feature lets you restore the entire system if necessary. Network Appliance's implementation also lets end users restore individual files from the snapshots. I tried this feature, and it worked flawlessly.

As valuable as the Snapshot feature is, you still need to perform a full backup to tape in the event of a catastrophe. But unlike typical servers, which might require the system to be down for hours during a backup, the F740 requires that you shut down your database for only a minute or two while the server takes the snapshot. You can then perform the tape backup in the background from the snapshots. An optional software package called SnapMirror can take snapshots and transmit them to a remote Network Appliance file server.

Network Appliance provides a full complement of printed hardware and software manuals. Each is well organized, and the hardware manuals are well illustrated. Much of the printed information is also available on CD-ROM as HTML and Portable Document Format (PDF) files. The F740 comes with a 1-year parts-and-labor warranty, which includes 24 x 7 toll-free technical support. Although the company offers additional service plans, the warranty period is a little short considering the system's price.

The F740 provides excellent performance, enormous capacity, good server management features, and multiprotocol support. But you need to balance these attributes against the price. Some new Profusion-based 8-way servers have similar prices and can accomplish tasks other than file service. However, these servers lack multiprotocol support, and the Lab's early 8-way tests suggest that the F740 is a faster file server. The F740's value also depends on your environment. If adding new file servers means you must upgrade your air conditioning system or add floor space, the F740 might be just the ticket. And if you already have a large file-server farm, the F740's speed, short backup window, and reduced management overhead might be difficult to pass up.