Data lost during replication

From: Peter Jones (anonymous_at_discussions.microsoft.com)
Date: 03/19/04 

Date: Thu, 18 Mar 2004 18:36:06 -0800

Sorry if this is a double post. I sent the following about six hours ago and it still hasn't appeared on the forum so I'm sending again...

Hi,
I'm in pre-deployment testing mode for a replicated system using star topology over dial-up lines. All my prior testing has been over a LAN and everything has been fine. My environment is:
1) Access 2000
2) Windows 2000 IIS Server at the Hub and Windows 2000 on remotes laptops. Latest SP’s installed along with MDAC 2.8.
3) The laptops connect directly into LAN via secure dial-up connection, i.e. not via the Internet.
4) The Synchronizer on the Hub is configured for "Indirect Synchronization". The order of synchronization attempts is: Indirect, Internet, Direct.
5) The Hub database has now been configured to its maximum expected size - 100,000 master records and 1,000,000 child records. It is 300Mb big.
6) The large database initially caused problems with running out of locks and MaxLocksPerFile, in the Jet registry, was increased from 9,000 to 32,000. This change fixed that particular problem.
7) A global replica was created and put on a laptop.
8) The hub and laptop were synchronized over the LAN using the Access UI (normally the synchronization is done programmatically).
9) 200 master and 800 child records were added at the laptop and the databases synchronized again over the LAN without problems. The synchronization was done programmatically and took ~ 1 minute.
10) The LAN connection between the two systems was removed and dial-up connection established (connect speed 21K).
11) Again, 200 master and 800 child records added to the laptop database.
12) Synchronization was started and left to run overnight (hadn't completed 1.5 hours after starting).
13) This morning the Laptop had stopped with a "delayed write error". This is a known problem to me that was fixed by turning of write caching on the disk. However I had forgotten to do that for this test but it is not the reason for this post.
14) On examining the Laptop I can see that, up to point of the “delayed write error”, 27Mb of data had been sent on the dial-up connection and 19Mb had been received.
15) The laptop database was in its original state but, on the Hub database, about 97,000 master and 970,000 child records had been deleted.

Q1. Why so much network traffic when so few new records had been created and ready for replication?

Q2. Why were the records deleted from the Hub?

Any comments, suggestions or wild guesses would be appreciated.

Cheeers, Peter

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