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Thread 3.x file and server mode... Index Buffer Corrupt...
Mon, Dec 15 2008 5:19 AMPermanent Link

durumdara
Hi!

We have a problem in more of our customers.
We got index page buffer corrupt errors, or other index errors.
We daily reindex the tables, but the errors are return again.

To solve this problem, one place we substituted the file mode to server mode.

But the errors are continued. Yesterday the sysadmin reported us that the net card of one
client is wrong, and this problem vanished in this place.

I wanna ask that why the server not filter these kind of errors?

Because I thought before this operation that when the dbsrvr.exe got the data packet, it
is check all packet before it is write the data to the file...

But after this "accident" I saw that nothing happened - the wrong client's machine can
corrupt the database! In server mode too...

I wanna ask that how to solve this problem? If I set the "internet" type to database can I
filter these kind of errors?
I wanna know because another places we got same problems, and I wanna filter the wrong
data packets, wrong updates...

Thanks for your help:
 dd
Mon, Dec 15 2008 10:05 AMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

<< We have a problem in more of our customers.
We got index page buffer corrupt errors, or other index errors.
We daily reindex the tables, but the errors are return again.

To solve this problem, one place we substituted the file mode to server
mode.

But the errors are continued. Yesterday the sysadmin reported us that the
net card of one client is wrong, and this problem vanished in this place.

I wanna ask that why the server not filter these kind of errors? >>

Are you sure that you had everyone using remote sessions and accessing the
server ?  It is impossible to get index corruption issues due to networking
problems when using remote sessions accessing the DBISAM Database Server.
What will happen is that you'll get errors when the data is unpacked on
either end.

--
Tim Young
Elevate Software
www.elevatesoft.com

Mon, Dec 15 2008 10:40 AMPermanent Link

durumdara
"Tim Young [Elevate Software]" <timyoung@elevatesoft.com> wrote:

<< We have a problem in more of our customers. I wanna ask that why the server not filter
these kind of errors? >>
>Are you sure that you had everyone using remote sessions and accessing the
>server ?

I tried to make safe applications which disable the using of this table (except one that
uses the table as server mode).

> It is impossible to get index corruption issues due to networking
> problems when using remote sessions accessing the DBISAM Database Server.
> What will happen is that you'll get errors when the data is unpacked on
> either end.

We have more time experience with this effect (client machine errors corrupt databases),
but I'm not sure which case happened in server mode.
Except this - but I'm not sysadmin to check all access in this customer (far-far away...),
so everything is possible.

But:
Can I use "internet" mode to test packet validity?
As I know this mode compress the data. But I'm not sure that it have CRC, or other inner
structure to test validity, or not...

Thanks for your help:
 dd
Wed, Dec 17 2008 12:26 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

<< Can I use "internet" mode to test packet validity? >>

We don't do "packets", that's done at below the TCP/IP stream level.  We
simply use Winsock to send and receive streams of data, which are guaranteed
by TCP/IP to be sent, or not sent, in their entirety.  It is impossible to
have something not come through as it was sent with TCP/IP.  That's one of
its signature features.

However, this is all besides the point, because any deviation or corruption
of the sent data will simply cause an exception on the receiving end, and
will never get anywhere near the tables or indexes.

--
Tim Young
Elevate Software
www.elevatesoft.com

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