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Understanding and configuring Registry Size Limit (RSL)

This article was previously published under Q124594
This article has been archived. It is offered "as is" and will no longer be updated.
This article describes Registry Size Limit (RSL) and tells how to configure it.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

By default, RSL is 25 percent of the size of paged pool. Setting up thesize of paged pool (see PagedPoolSize value of the Registry keyHKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\MemoryManagement) also affects the size of RSL.

You can also manually set the RSL:

  1. Run the Registry Editor (REGEDT32.EXE).
  2. Locate the key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control.
  3. Modify the value RegistrySizeLimit (create it first it if it does not already exist) to reflect the desired size, in terms of bytes.

    NOTE: RegistrySizeLimit must have a type of REG_DWORD, and a data length of 4 bytes, or it is ignored. If you set the value RegistrySizeLimit to less than 4 megabytes (MB), it is forced up to 4 MB. If you set it to greater than about 80 percent of the size of paged pool, it is set down to 80 percent of the size of paged pool (it is assumed that paged pool is always more than 5 MB). If you set it to 0xffffffff the maximum size allowable (or 80 percent of paged pool, up to 102 MB) is set.
  4. Shut down and restart Windows NT for changes in RSL to take effect.
Note A system restart is required after the RSL has been increased either through the graphical user interface (GUI) or the registry, because this change does not happen dynamically. If you do not restart the system, you may experience the following event:

Event Type: Error
Event Source: Userenv
Event Category: None
Event ID: 1000
Date: date
Time: time
User: NT AUTHORITY\SYSTEM Computer: name
Description: RegLoadKey failed. Return value Insufficient system resources exist to complete the requested service for C:\Documents and Settings\ntuser.dat.

In Windows NT 4.0, and Windows NT 4.0, Terminal Server Edition, the maximum paged pool size is 192 MB, so RSL can be a maximum of 153.6 MB. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
142719 NT Reports Out of Resources Error When Memory is Available
In Windows 2000, the maximum paged pool size is approximately 370-400 MB, when you do not use the /3gb command-line switch (this makes the RSL greater than 296 MB). If you use the /3gb switch, these values remain unchanged from Windows NT 4.0.

Additional Notes on RSL

RSL sets a maximum, not an allocation (unlike some other such limits in thesystem). Setting a large RSL will NOT cause the system to use that muchspace unless it is actually needed by the Registry. It also does NOTguarantee that that much space will be available for use in the Registry.

In Windows NT version 3.1, paged pool defaults to 32 MB, so the default RSLis 8 MB (enough to support approximately 5000 user accounts). In Windows NT3.5, paged pool can be set to a maximum of 128 MB, so RSL can be no largerthan about 102 MB (enough to support approximately 80,000 users; however,other system limitations might keep this number of users considerablylower).

RSL includes space in the hives themselves, as well as some of theRegistry's runtime structures. Other runtime structures are either billedagainst standard quota, or are protected by size limits and serialization.

To ensure that you can always at least boot and edit the Registry if youset RSL incorrectly, quota checking is not turned on until after the firstsuccessful loading of a hive (that is, loading a user profile).

For all but a few domain controllers, RSL never needs to be changed.

The limitations imposed by RSL are approximate.

For more information on the Registry size limit, search on the keyword"RegistrySizeLimit" in the Windows NT Registry Entries Help file found inthe Windows NT version 3.5 Resource Kit, or query on the following keywordin the Microsoft Knowledge Base:


This limitation and the UI have been removed in Windows XP and in Windows Server 2003. Please see the following article for more information.
292726 Registry Size Limit functionality has been removed from Windows Server 2003 and from Windows XP

Article ID: 124594 - Last Review: 12/04/2015 10:58:56 - Revision: 4.4

Microsoft Windows 2000 Server, Microsoft Windows 2000 Advanced Server, Microsoft Windows 2000 Professional Edition, Microsoft Windows 2000 Datacenter Server, Microsoft Windows NT Workstation 3.5, Microsoft Windows NT Workstation 3.51, Microsoft Windows NT Workstation 4.0 Developer Edition, Microsoft Windows NT Server 3.5, Microsoft Windows NT Server 3.51, Microsoft Windows NT Server 4.0 Standard Edition

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