Startup parameters for the NT Server service

by Wayne Maples [Published on 20 April 2004 / Last Updated on 20 April 2004]

The startup parameters for the Windows NT Server Service are:

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\LanmanServer\Parameters
Name: AlertSched
Type: REG_DWORD
Value: 1 to 65535 minutes. Default=5
Specifies in Microsoft LAN Manager and in Windows NT how often the server checks alert conditions and sends needed alert messages.

Name: Announce
Type: REG_DWORD
Value: 1 to 65535 seconds. Default=240
Specifies how often a nonhidden server announces itself (broadcasts) to the network.

Name: AnnDelta
Type: REG_DWORD
Value: 0 to 65535 milliseconds. Default=3000
Specifies the time by which the announcement period can vary. This helps to prevent several servers from continuously announcing simultaneously.

Name: Autodisconnect
Type: REG_DWORD
Value: 0 to 4294967295 minutes.
Specifies the time by which unused LAN connections are disconnected. See a138365.

Name: BlockingThreads
Type: REG_DWORD
Value: 1 to 9999
Specifies the number of threads set aside by the server to service requests that can block the thread for a significant amount of time. Larger values can increase performance but use more memory. A value that is too large can impede performance by causing excessive task switching. I wouldn't touch this one. Not clear what default is but this is not a value a server admin should need to fiddle with.

Name: Comment
Type: REG_SZ
Value: Default is null.
Provides the server's comment. This is sent in announcements and returned to NetServerGetInfo requests.

Name: ConnectionlessAutoDisc
Type: REG_DWORD
Value: 15 to 65535 minutes. Default=15
Disconnect time for clients using direct hosted IPX. If the client does not send a request to the server during this interval, the client is disconnected regardless of whether it has open files or pipes. Disconnecting from a connection to basic network services on a Windows NT Server using the IPX protocol results in a license being held upon disconnection for up to the time value of the ConnectionlessAutoDisc function, which is a minimum of 15 minutes. In other words, this is the amount of time that it will take to free up that license for use by others, and you cannot shorten it. However, if you reconnect within that 15-minute period, you will use the same license and not consume another one.

Name: CriticalThreads
Type: REG_DWORD
Value: 1 to 9999 Default=1
Special-purpose threads used for time-critical tasks.

Name: Disc
Type: REG_DWORD
Value: 0 to 0xFFFFFFFF minutes Default=15
Specifies the amount of idle time that a circuit is allowed before being disconnected. If the virtual circuit has any open files or searches, it is not automatically disconnected. If this parameter is set to a low value, it saves server resources but hinders performance because of clients' overhead in reconnecting. This is equivalent to autoDisconnect in Microsoft LAN Manager.

Name: DiskSpaceThreshold
Type: REG_DWORD
Value: 0 to 99 percent. Default=10
Specifies the percentage of free disk space remaining before an alert is sent. This generates an Error 2013.

Name: EnableFCBopens
Type: REG_DWORD
Value: 0 or 1 true or false. Default=1 (true)
Specifies whether MS-DOS File Control Blocks (FCBs) are folded together, so multiple remote opens are performed as a single open on the server. This saves resources on the server.

Name: EnableOplockForceClose
Type: REG_DWORD
Value: 0 or 1 true or false. Default=0 (false)
If a client has an opportunistic lock (oplock) and does not respond to an oplock break, there are two possible behaviors that this parameter selects:

  • 0 (false) : Fail the second open, thereby limiting access to the file.
  • 1 (true) : Force closed the open instance of the client that has the oplock, risking the loss of cached data.

Name: EnableOplocks
Type: REG_DWORD
Value: 0 or 1 true or false. Default=1 (true)
Specifies whether the server allows clients to use oplocks on files. Oplocks are a significant performance enhancement, but have the potential to cause lost cached data on some networks, particularly wide-area networks.

Name: EnableRaw
Type: REG_DWORD
Value: 0 or 1 true or false. Default=1 (true)
Specifies whether the server processes raw Server Message Blocks ( SMBs ). If enabled, this allows more data to be transferred per transaction and improves performance. However, it is possible that processing raw SMBs can impede performance on certain networks. This parameter is automatically tuned by the server. don't twiddle here

Name: EnableSoftCompat
Type: REG_DWORD
Value: 0 or 1 true or false. Default=1 (true)
Specifies whether the server maps a request to a normal open request with shared-read access when the server receives a compatibility open request with read access. Mapping such requests allows several MS-DOS computers to open a single file for read access. However, this feature can potentially cause functionality problems with some MS-DOS applications.

Name: ErrorThreshold
Type: REG_DWORD
Value: 1 to 65535 Default=10
Sets the number of errors that can occur within an AlertSched interval before the server sends an altert message.

Name: Hidden
Type: REG_DWORD
Value: 0 or 1 true or false. Default=0 (false)
If this parameter is disabled, the server's name and comment can be viewed by others on the domain. If enabled, the server's name and comment will not be announced.

Name: InitConnTable
Type: REG_DWORD
Value: 1 to 128 Default=8
Specifies the initial number of tree connections to be allocated in the connection table. The server automatically increases the table as necessary, so setting the parameter to a higher value is an optimization.

Name: InitFileTable
Type: REG_DWORD
Value: 1 to 256 Default=16
Specifies the initial number of file entries to be allocated in the file table of each server connection.

Name: InitSearchTable
Type: REG_DWORD
Value: 1 to 2048 Default=8
Specifies the initial number of entries in the connection's search table.

Name: InitSessTable
Type: REG_DWORD
Value: 1 to 64 Default=4
Specifies the initial number of session entries to be allocated in the session table of each server connection.

Name: InitWorkItems
Type: REG_DWORD
Value: 1 to 512 Default=??
Specifies the initial number of receive buffers, or work items, used by the server. Allocating work items costs a certain amount of memory initially, but not as much as having to allocate additional buffers later.

Name: IRPstackSize
Type: REG_DWORD
Value: 1 to 12 Default=4
Specifies the number of stack locations in I/O Request Packets ( IRPs ) used by the server. It may be necessary to increase this number for certain transports, MAC drivers, or local file system drivers. Each increment costs 36 bytes of memory per work item (that is, #work items * 36 bytes = total memory cost).

Name: LinkInfoValidTime
Type: REG_DWORD
Value: 0 to 100,000 seconds. Default=60
Specifies the amount of time during which the transport link information is still valid. If more than this amount of time has passed since the last query, the server requires transport link information.

Name: MaxFreeConnections
Type: REG_DWORD
Value: 2 to 8
Specifies the maximum number of free connection blocks maintained per endpoint.

Name: MaxLinkDelay
Type: REG_DWORD
Value: 0 to 100,000 seconds. Default=60
Specifies the maximum time allowed for a link delay. If delays exceed this number, the server disablesraw I/O for this connection.

Name: MaxKeepSearch
Type: REG_DWORD
Value: 10 to 10000 seconds. Default=1800
Specifies the maximum time during which an incomplete MS- DOS search will be kept by the server. Larger values ensure better interoperability with MS- DOS utilities such as tree-copy and delete-node. However, larger values can cause unusual local behavior (such as a failure of a local directory-delete operation) and higher memory use on the server.

Name: MaxMpxCt
Type: REG_DWORD
Value: 1 to 100 requests. Default=50
Provides a suggested maximum to clients for the number of simultaneous requests outstanding to this server. A higher value can increase server performance but requires higher use of server work items.

Name: MaxNonpagedMemoryUsage
Type: REG_DWORD
Value: 1 to 0xFFFFFFFF requests.
Specifies the maximum size of nonpaged memory that the server can have allocated at any time. Adjust this parameter if you want to administer memory quota control.

Name: MaxPagedMemoryUsage
Type: REG_DWORD
Value: 1 to 0xFFFFFFFF requests.
Specifies the maximum size of pageable memory that the server can have allocated at any time. Adjust this parameter if you want to administer memory quota control.

Name: MaxWorkItems
Type: REG_DWORD
Value: 1 to 512
Specifies the maximum number of receive buffers, or work items, the server can allocate. If this limit is reached, the transport must initiate flow control at a significant performance cost.

Name: MaxWorkItemIdleTime
Type: REG_DWORD
Value: 10 to 1800 seconds. Default=300
Specifies the amount of time that a work item can stay on the idle queue before it is freed.

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