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Search our Knowledge Base for technical articles. This database may contain information sourced from other sites.
You can enter up to 100 characters in your search term. We continue to add articles in this database as we encounter issues in our support work.
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| Opportunistic Locking |
Disabling Read Caching on Windows Workstations
All Windows operating systems in the 9X family that act as database clients for DataFlex data files (meaning that they access DataFlex data files stored on other Windows PCs) need to have read caching disabled in order to minimize the chances of database corruption. This includes Windows 98 and Windows ME.
The Windows registry entry that controls read caching on Windows network clients is:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VxD\VREDIR
DiscardCacheOnOpen REG_BINARY 0 or 1
Default: 0 (not disabled)
To disable read caching, the value of DiscardCacheOnOpen must be set to 1.
You can verify (or change or add, if necessary) this Registry value using the Windows Registry Editor (regedit.exe).
If you do change this Registry value, you will have to reboot the PC to ensure that the new setting goes into effect.
Please read the Microsoft disclaimer regarding editing of the Windows registry here.
STEPS:
1. Start > Run > Regedit.exe
2. Click on the + (plus sign) next to HKey_Local_Machine
3. Click on the + (plus sign) next to System
4. Click on the + (plus sign) next to CurrentControlSet
5. Click on the + (plus sign) next to Services
6. Click on the + (plus sign) next to VxD
7. Click on the VREDIR entry on the left-hand side of Registry Editor
8. If the DiscardCacheOnOpen registry value already exists (on the right-hand side of Registry Editor), ensure that its value is 1
9. If the DiscardCacheOnOpen value already exists but its value is not 1, double-click on DiscardCacheOnOpen to change its value to 1
10. If the DiscardCacheOnOpen entry does not exist, right-click in the white space of the right-hand side of Registry Editor
11. Select New > Binary value
12. Rename the value to DiscardCacheOnOpen
13. Double-click on DiscardCacheOnOpen to change its value to 1
Disabling Opportunistic Locking on Windows Servers
All Windows operating systems in the NT family that act as database servers for DataFlex data files (meaning that DataFlex data files are stored there and accessed by other Windows PCs) need to have opportunistic locking disabled in order to minimize the chances of database corruption. This includes Windows NT, Windows 2000, Windows XP and Windows 2003 Server.
There are 2 Windows registry entries that control opportunistic locking (oplocks) on Windows network servers:
1. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters EnableOpLockForceClose
2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters EnableOplocks
1. EnableOpLockForceClose
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
EnableOpLockForceClose REG_DWORD 0 or 1
Default: 0 (not disabled)
To disable oplocks, the value of EnableOpLockForceClose must be set to 1.
You can verify (or change or add, if necessary) this Registry value using the Windows Registry Editor (regedit.exe).
If you do change this Registry value, you will have to reboot the PC to ensure that the new setting goes into effect.
Please read the Microsoft disclaimer regarding editing of the Windows registry here.
STEPS:
1. Start > Run > Regedit.exe
2. Click on the + (plus sign) next to HKey_Local_Machine
3. Click on the + (plus sign) next to System
4. Click on the + (plus sign) next to CurrentControlSet
5. Click on the + (plus sign) next to Services
6. Click on the + (plus sign) next to LanManServer
7. Click on the Parameters entry on the left-hand side of Registry Editor
8. If the EnableOpLockForceClose registry value already exists (on the right-hand side of Registry Editor), ensure that its value is 1
9. If the EnableOpLockForceClose value already exists but its value is not 1, double-click on EnableOpLockForceClose to change its value to 1
10. If the EnableOpLockForceClose entry does not exist, right-click in the white space of the right-hand side of Registry Editor
11. Select New > DWORD value
12. Rename the value to EnableOpLockForceClose
13. Double-click on EnableOpLockForceClose to change its value to 1
2. EnableOplocks
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
EnableOplocks REG_DWORD 0 or 1
Default: 1 (true)
To disable oplocks, the value of EnableOplocks must be set to 0.
You can verify (or change or add, if necessary) this Registry value using the Windows Registry Editor (regedit.exe).
If you do change this Registry value, you will have to reboot the PC to ensure that the new setting goes into effect.
Please read the Microsoft disclaimer regarding editing of the Windows registry here.
STEPS:
1. Start > Run > Regedit.exe
2. Click on the + (plus sign) next to HKey_Local_Machine
3. Click on the + (plus sign) next to System
4. Click on the + (plus sign) next to CurrentControlSet
5. Click on the + (plus sign) next to Services
6. Click on the + (plus sign) next to LanManServer
7. Click on the Parameters entry on the left-hand side of Registry Editor
8. If the EnableOplocks registry value already exists (on the right-hand side of Registry Editor), ensure that its value is 0
9. If the EnableOplocks value already exists but its value is not 0, double-click on EnableOplocks to change its value to 0
10. If the EnableOplocks entry does not exist, right-click in the white space of the right-hand side of Registry Editor
11. Select New > DWORD value
12. Rename the value to EnableOplocks
13. Double-click on EnableOplocks to change its value to 0
Note: The location of the registry entry for opportunistic locking has changed in Windows 2000 from the earlier location in Microsoft Windows NT. In Windows 2000, the registry entry that disables opportunistic locking is:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MRXSmb\Parameters\
OplocksDisabled REG_DWORD 0 or 1
Default: 0 (not disabled)
To disable oplocks, the value of OplocksDisabled must be set to 1.
Note: Windows 2000 will still respect the EnableOplocks registry value used to disable oplocks in earlier versions of Windows.
Disabling Opportunistic Locking on Windows Workstations
All Windows operating systems in the NT family that act as database servers for DataFlex data files (meaning that DataFlex data files are stored there and accessed by other Windows PCs) need to have opportunistic locking disabled in order to minimize the chances of database corruption. This includes Windows NT, Windows 2000 and Windows XP.
If you use a Windows NT family workstation in place of a server, you must also disable opportunistic locking (oplocks) on that workstation. For example, if you use a PC with the Windows NT Workstation operating system instead of Windows NT Server, Windows 2000 Professional instead of Windows 2000 Server, or Windows XP Home instead of Windows XP Professional, and you have DataFlex data files located on it that are accessed from other Windows PCs, you will need to disable oplocks on that system.
The major difference is the location in the Windows registry where the values for disabling oplocks are entered. Instead of the LanManServer location, the LanManWorkstation location is used here.
There are 2 Windows registry entries that control opportunistic locking (oplocks) on Windows network workstations:
1. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters EnableOpLockForceClose
2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters EnableOplocks
1. EnableOpLockForceClose
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters
EnableOpLockForceClose REG_DWORD 0 or 1
Default: 0 (not disabled)
To disable oplocks, the value of EnableOpLockForceClose must be set to 1.
You can verify (or change or add, if necessary) this Registry value using the Windows Registry Editor (regedit.exe).
If you do change this Registry value, you will have to reboot the PC to ensure that the new setting goes into effect.
Please read the Microsoft disclaimer regarding editing of the Windows registry here.
STEPS:
1. Start > Run > Regedit.exe
2. Click on the + (plus sign) next to HKey_Local_Machine
3. Click on the + (plus sign) next to System
4. Click on the + (plus sign) next to CurrentControlSet
5. Click on the + (plus sign) next to Services
6. Click on the + (plus sign) next to LanManWorkstation
7. Click on the Parameters entry on the left-hand side of Registry Editor
8. If the EnableOpLockForceClose registry value already exists (on the right-hand side of Registry Editor), ensure that its value is 1
9. If the EnableOpLockForceClose value already exists but its value is not 1, double-click on EnableOpLockForceClose to change its value to 1
10. If the EnableOpLockForceClose entry does not exist, right-click in the white space of the right-hand side of Registry Editor
11. Select New > DWORD value
12. Rename the value to EnableOpLockForceClose
13. Double-click on EnableOpLockForceClose to change its value to 1
2. EnableOplocks
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanManWorkstation\Parameters
EnableOplocks REG_DWORD 0 or 1
Default: 1 (true)
To disable oplocks, the value of EnableOplocks must be set to 0.
You can verify (or change or add, if necessary) this Registry value using the Windows Registry Editor (regedit.exe).
If you do change this Registry value, you will have to reboot the PC to ensure that the new setting goes into effect.
Please read the Microsoft disclaimer regarding editing of the Windows registry here.
STEPS:
1. Start > Run > Regedit.exe
2. Click on the + (plus sign) next to HKey_Local_Machine
3. Click on the + (plus sign) next to System
4. Click on the + (plus sign) next to CurrentControlSet
5. Click on the + (plus sign) next to Services
6. Click on the + (plus sign) next to LanManWorkstation
7. Click on the Parameters entry on the left-hand side of Registry Editor
8. If the EnableOplocks registry value already exists (on the right-hand side of Registry Editor), ensure that its value is 0
9. If the EnableOplocks value already exists but its value is not 0, double-click on EnableOplocks to change its value to 0
10. If the EnableOplocks entry does not exist, right-click in the white space of the right-hand side of Registry Editor
11. Select New > DWORD value
12. Rename the value to EnableOplocks
13. Double-click on EnableOplocks to change its value to 0
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