Oplocks will kill us all

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Tom
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Joined: Thu Jan 28, 2010 12:59 am
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Re: Oplocks will kill us all

#11 Post by Tom »

@Brian: Just for your understanding. Opportunistic locking is a mechanism intended for speed improvements, which causes entire files to be cached on the client workstation. It's easy to understand that this will cause problems in file sharing scenarios, as we all have with DBF based applications. There are two major problems: Cached files need to be transferred very often, and all the caches need to be synchronized permanentely. This may lead to file corruption. To be honest, we never faced data problems really caused by this. The errors we got from customers with data integrity problems were mainly caused by bad networks, and what oplock-settings we tried, they never solved those problems. So we installed ADS on those (few) sites.

ADS (NOT ADS local!) is a server software. With ADS, files are not opened by the app, but on the server by the ADS. This is not effected by oplocking, since the client does not deal with files. You don't need to care about oplocking within a client/server scenario. Files opened by the ADS are cached anyway, but all those files are only opened once, no matter how often your app uses them.

Edit: I wonder how a SQL-app should be effected by oplock settings, as you mentioned in your intial posting. What registry settings did you manipulate to cause Quickbooks to fail?
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Tom

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rdonnay
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Re: Oplocks will kill us all

#12 Post by rdonnay »

Another piece of info from Steffen:
Just a quick side note for you. The ADS Server also has its problems with SMB2 for details

see: http://devzone.advantagedatabase.com/dz ... 90707-2191

Of course the smb2 msi package at www.alaska-software.com/smb2 from Alaska also resolves
the ADS issues.
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