Determining the Number of File Servers
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
The following section describes reasons why you might want to deploy additional file servers and how you can determine the number of file servers that you require.
Consolidating Older File Servers
Many organizations today are consolidating older file servers throughout the organization into fewer larger, more powerful file servers. Consolidation reduces the cost of managing multiple file servers and increases the efficiency of storage allocation and backup tasks.
If you plan to consolidate file servers running Windows NT 4.0 or Windows 2000 onto new file servers running Windows Server 2003, determine the number of file servers running Windows Server 2003 that is necessary to match or exceed the performance of your existing file servers. You can derive these figures by using the scaling factors provided in "Determining RAM and CPU Specifications" earlier in this chapter.
The following scenarios describe two consolidation situations based on the scaling factors presented in "Determining RAM and CPU Specifications" earlier in this chapter.
Scenario 1: Consolidating file servers running Windows NT Server 4.0
An organization plans to migrate its file services to file servers running Windows Server 2003. It currently has 100 Windows NT 4.0 file servers with the following hardware:
UP Pentium Pro, 200 MHz
256 MB RAM
Fast Ethernet network adapters
The organization plans to use the following hardware to consolidate file servers:
4P 900-MHz Intel® Pentium® III Xeon™
3 GB RAM
Gigabit network adapters
To determine the number of file servers the organization needs when migrating to Windows Server 2003, use the scaling factors described in Table 2.20.
Table 2.20 Consolidating File Servers Running Windows NT Server 4.0
| Area of Improvement | Details | Scaling Factor |
|---|---|---|
Operating system |
As shown in Table 2.12, migrating from Windows NT 4.0 to Windows Server 2003 provides a 2.75X performance improvement. |
2.75X |
Hardware upgrade |
As shown in Table 2.13, migrating from a Pentium Pro, 200 MHz, to a Xeon, 900 MHz, provides a 4X performance improvement. |
4X |
Processor scaling |
As shown in Table 2.14, migrating from UP (one processor) servers to 4P servers provides a 1.8X performance improvement. |
1.8X |
Total improvements |
Multiply the scaling factors (2.75 x 4 x 1.8) |
19.8X |
Based on these figures, the organization can migrate 100 file servers running Windows NT 4.0 to five 4P Xeon 900-MHz servers running Windows Server 2003. (To derive this number, divide 100 by 19.8.) The organization must also be sure that the five Xeon servers have adequate storage space to store the consolidated data, as well as future data, and that 3 GB of memory can handle the total workload of the 100 servers.
Scenario 2: Consolidating file servers running Windows 2000 Server
An organization plans to migrate its file services to file servers running Windows Server 2003. It currently has five Windows 2000 file servers with the following hardware:
4P 400-MHz Intel® Pentium® II Xeon™
1 GB RAM
Gigabit network adapters
The organization plans to use the following hardware to consolidate file servers:
8P 900-MHz Intel® Pentium® III Xeon™
4 GB RAM
Gigabit network adapters
To determine the number of file servers the organization needs when migrating to Windows Server 2003, use the scaling factors described in Table 2.21.
Table 2.21 Consolidating File Servers Running Windows 2000 Server
| Area of Improvement | Details | Scaling Factor |
|---|---|---|
Operating system |
As shown in Table 2.12, migrating from Windows 2000 Server to Windows Server 2003 provides a 2.2X performance improvement. |
2.2X |
Hardware upgrade |
As shown in Table 2.13, migrating from a Xeon, 400 MHz, to a Xeon, 900 MHz, provides a 2X performance improvement. |
2X |
Processor scaling |
As shown in Table 2.14, migrating from 4P servers to 8P servers provides a 1.3X performance improvement. |
1.3X |
Total improvements |
Multiply the scaling factors (2.2 x 2 x 1.3) |
5.7X |
Based on these figures, the organization can use a single 8P Xeon 900-MHz file server, assuming it has enough memory, disk, and network I/O available. To ensure the availability of the server, the organization should consider using a server cluster instead of a single stand-alone file server. For more information about increasing the availability of file servers, see "Planning File Server Availability" earlier in this chapter.
Providing Additional Storage
If your organization uses direct-attached storage for file servers, deploy as many file servers as it takes to meet your storage needs. If each of your file servers provides 500 GB of storage, and you need at least 2 TB of storage, you need a minimum of five file servers. You also need to provide the new file servers with enough processing power and memory to serve your clients. Use the factors described in "Determining RAM and CPU Specifications" earlier in this chapter.
Providing More Processing Power
If users experience delays when accessing file servers, there are a number of ways you can improve file server performance:
Enable the Offline Files feature so that clients cache files locally instead of going to the file server whenever they need a file. You can also use this feature to enable automatic caching for programs. When you enable program caching on a shared folder, and a user runs a program from the shared folder, Windows Server 2003 copies the application .exe and .dll files as they are used and runs the files from the client’s local cache, which reduces server load and network traffic. For simple programs that use a single .exe file, this feature enables the program to run correctly when the server is down or the client is not connected to the network. For programs that consist of multiple files (.exe and .dll), all files must be cached on the local computer so that the program can run while offline. The user can ensure that all files are cached by choosing the Make Available Offline option from the File menu in Windows Explorer. For more information about the Offline Files feature, see "Offline settings for shared resources" and "Make a file or folder available offline" in Help and Support Center for Windows Server 2003.
Place copies of heavily used shared folders with primarily read-only files on multiple file servers, and use DFS to provide load sharing. If you also plan to use the Offline Files feature, note that you can use this feature in conjunction with DFS only for clients running Windows XP Professional. For more information about Offline Files, see "Offline Files overview" in Help and Support Center for Windows Server 2003.
Upgrade the processor, RAM, or disk subsystem in your existing file servers. Use the factors described in "Determining RAM and CPU Specifications" earlier in this chapter to determine the performance improvements you can gain by upgrading existing hardware.
Providing Same-Site Data Access for Users
If you have remote sites with expensive WAN links, you can deploy one or more file servers in those sites to provide users with fast, inexpensive LAN access to the file servers. For each site, take into account the storage and processing power needed by users in the site. You also need a backup and recovery procedure in place at each site in case one of the file servers fails.