DOCUMENT:Q103097  20-AUG-1993  [W_NT]
TITLE   :Access Violation (C0-C5) During Registry Backup or Save
PRODUCT :Windows NT
PROD/VER:3.10
OPER/SYS:WINDOWS
KEYWORDS:

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The information in this article applies to:
 
 - Microsoft Windows NT operating system, version 3.1
 - Microsoft Windows NT Advanced Server, version 3.1
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SYMPTOMS
========
 
During a backup or save of the Registry or one of its hives, an error
message is displayed on a blue screen and your system is halted. The
error message states that an access violation occurred (C0-C5). If you
perform a trace of the stack using Kernel Debugger, the Registry shows
up.
 
CAUSE
=====
 
The Registry has reached its capacity given its current Registry size
limit (RSL) and other system configuration factors. The RSL represents
the maximum size the Registry can reach and is 25 percent of the
paging file, by default. Since the paging file, by default, is 32 MB,
the default RSL is roughly 8 megabytes (MB). The default RSL is big
enough to store approximately 5000 users in the security accounts
manager (SAM) database. There is no guarantee that the amount of
memory specified by the RSL will be available.
 
RESOLUTION
==========
 
To avoid this problem, you must increase the RSL by either manually
editing the Registry entry for the RSL or by increasing the size of
the paging file. You can increase the size of the paging file by using
Control Panel. To modify the RSL in the Registry, do the following:
 
CAUTION: Modifying the Registry can harm your system. Query on these
keywords in the Microsoft Knowledge Base for details: KEYREG and
WARNING and NTADSRV.
 
1. Start Registry Editor (REGEDT32.EXE) and go to the following hive
   and subkey:
 
      HKEY_LOCAL_MACHINE, System\CurrentControlSet\Control
 
2. Select the RegistrySizeLimit value and Choose Edit Value from the
   Edit menu. If the RegistrySizeLimit value is not present, enter it
   by choosing Add Value from the edit menu and use the following
   information:
 
      RegistrySizeLimit : REG_DWORD : <bytes>
 
3. Enter the number of bytes for the RSL for the value of the
   RegistrySizeLimit value.
 
4. Exit Registry Editor and shut down Windows NT.
 
Registry Size Limit Notes
=========================
 
The RSL is a maximum boundary, not an allocation. Setting a large RSL
does not mean the system will use the specified amount of space unless
the Registry requires it; similarly, it does not imply that the
specified amount will be available.
 
If you set the RSL to a value less than 4 MB, it will round up to 4
MB. If it is greater than 80% of the paging file, it will be reduced
to just 80% of the paging file.
 
Setting the RSL to 0xffffffff instructs Windows NT to use as much of
the paging file as it can (80%). Since the paging file has a maximum
size of 128 MB, the RSL can be no larger than about 102 MB which would
support about 80,000 users in the SAM database.
 
The limitations imposed by the RSL are approximate.
 
Additional reference words: 3.10
KBCategory:
KBSubCategory: KEYREG STOPSCRN

=============================================================================

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Copyright Microsoft Corporation 1993.