Replication Failed due to Schema Mismatch 3


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This post was written by Third Tier consultant Jeremy Anderson. Jeremy will also be presenting at the Third Tier Brain Explosion

In the process of two recent migrations, an issue has snuck up on me. The initial symptoms have all been different, but the end result has been the same. Replication errors. For one client it first appeared even when the Migration Wizard was not able to disable the DHCP service on the source servers, for another it did not appear until the mail box move was attempted.

If you are suffering from these issues you will see replication errors in your NTFRS event logs. “having Trouble enabling Replication from…”

clip_image001

When you run a dcdiag, you will get an error similar to the following:

Microsoft Windows [Version 5.2.3790]

(C) Copyright 1985-2003 Microsoft Corp.

C:Documents and SettingsContoso>dcdiag /s:ContosoSBS

Domain Controller Diagnosis

Performing initial setup:

Done gathering initial info.

Doing initial required tests

Testing server: Default-First-Site-NameContosoSBS

Starting test: Connectivity

……………………. ContosoSBS passed test Connectivity

Doing primary tests

Testing server: Default-First-Site-NameContosoSBS

Starting test: Replications

REPLICATION LATENCY WARNING

ContosoSBS: This replication path was preempted by higher priority work.

from Old-Server to ContosoSBS

Reason: The replication operation failed because of a schema mismatch between the servers involved.

The last success occurred at 2011-07-09 12:29:54.

Replication of new changes along this path will be delayed.

REPLICATION LATENCY WARNING

ContosoSBS: This replication path was preempted by higher priority work.

from Old-Server to ContosoSBS

Reason: The replication operation failed because of a schema mismatch between the servers involved.

The last success occurred at 2011-07-09 12:29:51.

Replication of new changes along this path will be delayed.

REPLICATION LATENCY WARNING

ContosoSBS: This replication path was preempted by higher priority work.

from Old-Server to ContosoSBS

Reason: The replication operation failed because of a schema mismatch between the servers involved.

The last success occurred at 2011-07-09 12:24:50.

Replication of new changes along this path will be delayed.

REPLICATION LATENCY WARNING

ContosoSBS: This replication path was preempted by higher priority work.

from Old-Server to ContosoSBS

Reason: The replication operation failed because of a schema mismatch between the servers involved.

The last success occurred at 2011-07-09 12:24:39.

Replication of new changes along this path will be delayed.

If you open a command prompt, and on the new SBS 2011 Server and you do a repadmin /showrepl you will get a reply that also indicates DNS and Replica Link Errors.

C:Documents and SettingsContosoSupport>repadmin /showrepl

repadmin running command /showrepl against server localhost

Default-First-Site-NameOld-Server

DC Options: IS_GC

Site Options: (none)

DC object GUID: 899d2bae-5a7b-44fe-bb2e-1a3f65221d34

DC invocationID: 276bef04-f1fd-4cd3-93e0-75b686c542f4

Source: Default-First-Site-NameContosoSBS

******* 9 CONSECUTIVE FAILURES since 2011-07-09 12:16:16

Last error: 8524 (0x214c):

The DSA operation is unable to proceed because of a DNS lookup failure.

Naming Context: CN=Schema,CN=Configuration,ContosoSBS,DC=lan

Source: Default-First-Site-NameContosoSBS

******* WARNING: KCC could not add this REPLICA LINK due to error.

Naming Context: ContosoSBS,DC=lan

Source: Default-First-Site-NameContosoSBS

******* WARNING: KCC could not add this REPLICA LINK due to error.

Naming Context: CN=Configuration,ContosoSBS,DC=lan

Source: Default-First-Site-NameContosoSBS

******* WARNING: KCC could not add this REPLICA LINK due to error.

All This sounds pretty nasty, and things are “just not right”. Never Fear. The fix is simple. Update your NIC drivers on your source server. Turn off RSS (Recive Side Scaling) and TOE (TCP Offload Engine)

   
 

Receive-Side Scaling (RSS) resolves the single-processor bottleneck by allowing the receive side network load from a network adapter to be shared across multiple processors. RSS enables packet receive-processing to scale with the number of available processors. This allows the Windows Networking subsystem to take advantage of multi-core and many core processor architectures.
http://technet.microsoft.com/en-us/network/dd277646

 
 

TCP Offload Engine or TOE is a technology used in network interface cards (NIC) to offload processing of the entire TCP/IP stack to the network controller. It is primarily used with high-speed network interfaces, such as gigabit Ethernet and 10 Gigabit Ethernet, where processing overhead of the network stack becomes significant.

http://en.wikipedia.org/wiki/TCP_Offload_Engine

clip_image003This has happened with on Broadcom and Intel Network card drivers. Once RSS and TOE are disabled, reboot the source server. Replication begins instantly, and you can carry on with your migration. Here is an Intel NIC with these options disabled:


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3 thoughts on “Replication Failed due to Schema Mismatch

  • Benjamin Gaudette

    From my side, I fixed the problem by deleting the replication between two DCs in AD Sites and Services, waited some times, till the error goes away and re-enabled the replication.

  • Richard M.

    I found that I actually did not have to reboot also the item was labelled differently but the second I disabled it I was able to force the replication. AMAZING why the hell Microsoft. ;tableflip

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