https://whatis.techtarget.com/definition/OpLock-opportunistic-lock
https://docs.microsoft.com/en-us/windows/desktop/FileIO/opportunistic-locks
https://support.microsoft.com/en-us/help/296264/configuring-opportunistic-locking-in-windows
https://cs.thomsonreuters.com/ua/acct_pr/acs/cs_us_en/kb/how-to-disable-opportunistic-locking-or-file-caching.htm
https://infusionsoftware.zendesk.com/hc/en-us/articles/115002293593-To-Disable-SMB2-and-OPLOCK-Network-Locking-Errors-

also keep in mind that Linux-based SMB uses other mechanisms (for instance if you have a simple NAS in your LAN

http://lug.krems.cc/docu/samba/ch05_05.html

and throw the above into Google translate...


https://www.graz4u.at/faq.html/weiterefragen/237-netapp-oplogs-deaktivieren.html

From another ISAM user in german the clear warning that you have to degrade to SMB1 before Oplock setting anipulation:
https://newyear2006.wordpress.com/2011/05/24/oplocks-oder-opportunistic-locking-lsst-einen-nicht-los-oder-wie-man-alte-16bit-clipper-programme-mit-server-2008-r2-fileshares-ans-laufen-bekommt/

and a thread in german, saying in essence we vfp users have no idea how the runtime implements access
https://social.msdn.microsoft.com/Forums/de-DE/594d5eea-c95e-437b-8ee4-8f0e2ad31b63/abschaltung-smb1-oplockproblematik?forum=foxprode

except probably Christoph Lange (ex Wollenhaupt), who probably has deciphered the runtime on that as well ;-)

>And also not familiar with "doevent sprinkling" - what is that?

the "s" must have been mistyped, should be "doevents sprinkling"
https://books.google.de/books?id=-6wGndJSbkcC&pg=PA243&lpg=PA243&dq=doevents+foxpro&source=bl&ots=7YG5FBMx9e&sig=6eu0L30NJXo2WLkc5OIh7T-RTUg&hl=de&sa=X&ved=2ahUKEwiYu-rB2o7dAhXPGewKHSBWC80Q6AEwBXoECAYQAQ#v=onepage&q=doevents%20foxpro&f=false

>Hi Thomas,
>
>I am familiar with the SMB registry settings (testing them now) and FLUSH...FORCE but not familiar with the OpLockSettings - is this also a registry setting and what does that do? And also not familiar with "doevent sprinkling" - what is that?
>
>Albert
>
>>First stop is to check SMB/SMB2 and OpLocksettings, then flush force and doevent sprinkling