Monitor system performance: Server 2003 has been designed for high performance immediately upon installation. However, it is always possible to tune the server settings for performance gains, which is why monitoring system performance is a natural part of system administration. We have already outlined some of the main tools using in monitoring and analyzing system performance earlier in this chapter, and we will be looking at some very specific counters later in the chapter.
However, this is a very good opportunity to take quick look at certain TCP parameters that you may want to monitor, as they can affect performance. Monitoring should always examine the hardware, the network and the workload so that the system can be tuned to meet performance goals.
TCP Parameters: There are certain TCP parameters that can be monitored and adjusted to improve server performance and increase throughput.
Parameter Description
TCPWindowSize This value determines the maximum amount of data (in bytes) that can be outstanding on the network at any given time. It can be set to any value from 1 to 65,535 bytes by using the following registry entry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip
\Parameters\TcpWindowSize (REG_DWORD)
Default settings:
Gigabit interface - 65,535
100 Mbps link - 16,384
Lower speeds - 8,192
Window Scaling For high bandwidth-delay products, like satellite links, you may need to increase window size over 64K. Modify the following registry entry: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
\Tcp1323Opts (REG_DWORD)
to 1 to enable window sizes of greater than 65,535. After you do this, you can modify TCPWindowSize to values up to 1GB.
MaxHashTableSize This value determines the size of the hash table holding the state of TCP connections. Default value is 128 * number of processors2. When a large concurrent connection load is expected on the system, set the following registry entry to a higher value: :HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip
\Parameters\MaxHashTableSize (REG_DWORD)
The maximum value is 0x10000 (65,536).
MaxUserPort A port is used whenever an active connection is used from a computer. Given the default value of available user mode ports (5,000 for each IP address) and TCP time-wait requirements, it may be necessary to make more ports available on the system. You can set the following registry entry to as high as 0xfffe (65534):
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip
\Parameters\MaxUserPort
Monitor file and print servers: The following section will outline some of the key parameters to utilize, specifically when fine-tuning performance on file and print servers under Server 2003.
Parameter Description
PagedPoolSize HKLM\System\CurrentControlSet\Control\Session Manager\MemoryManagement\ (REG_DWORD)
File cache space and paged pool space share a common area in system virtual address. Limiting the paged pool allows for a larger system cache, which causes more content to be cached and allows faster serving of files.
NtfsDisable8dot3NameCreation HKLM\System\CurrentControlSet\Control\FileSystem\ (REG_DWORD)
Default is 0. This parameter determines whether NTFS generates a short name in the 8.3 (DOS) naming convention for long file names and for file names that contain characters from the extended character set. If the value of this entry is 0, files can potentially have two names: the name that the user specifies and the short name that NTFS generates. If the name the user specifies conforms to the 8.3 naming convention, NTFS does not generate a short name.
Changing this value does not change the contents of a file, but it avoids the short-name attribute creation for the file, also changing the way NTFS displays and manages the file.
Disablelast access HKLM\System\CurrentControlSet\Control\FileSystem\. (REG_DWORD)
By default, this registry key is not created.
If you have an NTFS volume with a high number of folders or files, and a program is running that briefly accesses each of these in turn, the I/O bandwidth used to generate the Last Access Time updates can be a significant percentage of the overall I/O bandwidth. To increase the speed of access to a folder or file, you can set disablelastaccess to disable updating the Last Access Time. After you use this command and restart the computer, the Last Access Time is no longer updated. If you create a new file, the Last Access Time remains the same as the File Creation Time.
NumTcbTablePartitions HKLM\system\CurrentControlSet\Services\Tcpip\Parameters\. (REG_DWORD)
By default, this key is not created.
This parameter controls the number of TCB table partitions. The TCB table can be partitioned to improve scalability on multiprocessor systems by reducing contention on the TCB table.
TcpAck Frequency Note: TcpAckFrequency applies only to Windows Server 2003. The recommended setting for TcpAckFrequency is between one-third and one-half of TcpWindowSize.
For Gigabit cards:
HKLM\system\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
For each Gigabit adapter, add:
TcpAckFrequency (REG_DWORD) = 13 (decimal)
By default, this entry is not in the registry. If only acking data and not any control packets, ack once every 13 packets, instead of the default of two. This helps reducing packet processing costs for the Network Stack, in the case of large writes (uploads) from the client into the server.
For FastEthernet cards:
HKLM\system\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
For each FastEthernet adapter, add:
TcpAckFrequency (REG_DWORD) = 5 (decimal)
By default, this entry is not in the registry. If only acking data and not any control packets, ack once every five packets, instead of the default of two. This helps reducing packet processing costs for the Network Stack, in the case of large writes (uploads) from the client into the server.
Deborah Timmons is a Microsoft Certified Trainer and Microsoft Certified Systems Engineer. She came into the Microsoft technical field after six years in the adaptive technology field, providing technology and training for persons with disabilities. She is the President and co-owner of Integrator Systems Inc.
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