Re: MDAC question
From: Ralph (msnews.20.nt_consulting32_at_spamgourmet.com)
Date: 01/04/05
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Date: Tue, 4 Jan 2005 10:28:47 -0600
"Griff" <Howling@The.Moon> wrote in message
news:OLS3Rhl8EHA.1400@TK2MSFTNGP11.phx.gbl...
> I have an application that has two physical tiers.
>
> The application server runs VB6 code.
> The data server runs SQLServer 2000 (standard).
>
> Now and again, I get the following error reported:
>
> error -2147467259 - [DBNETLIB][ConnectionRead (recv()).]General
network
> error.
>
> Searching the internet, I came across the following document
>
> http://support.microsoft.com/kb/q175264/
>
> This article implied that the commandtimeout value should not be set to 0
> because of a bug in ADO 2.5. I think that timeouts should never be
> infinite, but hey, that's the code I've inherited....
>
> Anyhow, before changing all the VB code to use finite timeouts, I noted
that
> this article stated that the problem was fixed in MDAC 2.6. I therefore
> decided to check the MDAC versions on my two physical servers.
>
> Application Server: MDAC 2.71.9040.2
> Data Server: MDAC 2.80.1022.0
>
> I therefore have several questions:
>
> 1 - Is having two different versions of MDAC on the two tiers likely to
> cause a problem? How about with these particular versions.
>
> 2 - If different MDAC versions can cause problems, could they cause the
> ConnectionRead problem I'm experiencing.
>
> 3 - If I wish to standardise on one version of MDAC, is this a risk-free
> upgrade?
>
> 4 - MDAC may not be my problem - anyone experienced the error I've had
> before and fixed it? I can provide more details if required.
>
> Many thanks in advance
>
> Griff
>
First of all you are missing a major part of the question - what versions of
the ADO Data library are your applications using? What provider/driver
version are you using? The MDAC downloads are labeled by the highest/newest
ADO library supported but within its 50+ files is included all the earlier
versions. Newer features are supported in the newer Interfaces, but some
'bug fixes' are reflected in older ADO versions.
Having a different version of the MDAC components is likely not a problem -
as the ADO version you are using is obviously present or you would be
experiencing another problem (component not found). For example, I doubt
there is much difference between the ADO 2.6 data library supported by the
components in MDAC 2.7 and MDAC 2.8.
In general it is best to keep all of your MDAC components up-to-date with
the latest versions. But is that "risk free"? Nothing is absolutely
risk-free when it comes to changing out COM components. However, the MDAC
and ADO is one of the best 'COM' success stories out there. I have used a
policy of always upgrading servers and workstations to the latest MDAC as
part of a regular maintenance schedule and have only been burnt a couple of
times. [Of course, with a critical mission application/server this policy
may not be appropriate and possilbly job-threatening. <g>]
As for your network error, you will need to dig deeper than the ADO data
library version, and no simple answer is available without knowing more
about YOUR problem domain. I suggested that the ADO data library is likely
not the cause since ConnectionRead is called by drivers and providers.
Are you doing something cute with your connections - custom pooling, not
catching timeouts, errors, or other events?
Are you possibly blowing away connections without letting the server know?
Are you letting a connection 'hang-out' there for ever?
Have you enumerated the entire ADO Errors collection to make sure no other
information is available.
hth
-ralph
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