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Disturbing Windows 2000 Caching Problem
Message
De
19/06/2002 09:44:58
 
 
À
18/06/2002 16:10:08
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Divers
Thread ID:
00669860
Message ID:
00670109
Vues:
23
Please pardon my ignorance about caching. I will give you a scenerio where it seems that having the operating system cach at its own whimsey can only cause problems.

In our system we keep track of all of the parts required to make a metal building. We don't want more than one user modifying a building so we have a lock table. If user "A" wants to edit building "capital" the lock table is locked and searched for a record for the "capital" building. If it is not found, one is added and the table is then unlocked. If this record is still in cache and user "B" wants to edit the "capital" building he goes through the same process and is also given access to the "capital" building because user "A"'s lock record is still in cache. I have simplified the system for example sake but this sounds like a problem to me. It is not behavior that I expect.

>Yes, there was a lot of discussion of W2K and disk caching some time ago. The upshot seems to be: make sure all W2K machines in the loop (workstations and server, if applicable) are running Service Pack 2.
>
>http://www.levelextreme.com/wconnect/wc.dll?FournierTransformation~2,15,540525
>
>At a network level, you can consider disabling opportunistic locking on both server and workstations:
>
>http://support.microsoft.com/default.aspx?scid=kb;EN-US;q296264
>http://support.microsoft.com/default.aspx?scid=kb;EN-US;q126026
>http://support.microsoft.com/default.aspx?scid=kb;EN-US;q306981
>http://support.microsoft.com/default.aspx?scid=kb;EN-US;q224992
>
>Notwithstanding all of the above, there is no reason to be uneasy about a properly implemented cache; the CPU you're using to read this message no doubt implements one and you've never seen it fail or, I bet, even thought about it.
>
>The key phrase of course, is, "properly implemented". Maintaining cache coherency in a network file system is not trivial.
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