Article ID: 160850
Article Last Modified on 10/28/2006
APPLIES TO
- Microsoft Exchange Server 4.0 Standard Edition
- Microsoft Exchange Server 5.0 Standard Edition
- Microsoft Exchange Server 5.5 Standard Edition
This article was previously published under Q160850
SYMPTOMS
When a directory is restored from backup it attempts to get back copies of all the objects that it last modified or added and that it replicated out to other computers since it was backed up; this is called backsync. During backsync, you can get into a situation where it is not possible to make directory changes for up to 16 hours. When you attempt to modify the directory while it is in this state, the Microsoft Exchange Server Administrator program will display the following message:
The following event ID will also be logged:
CAUSE
This will most often occur after the restoration of a directory on a server that has the schedule on its connectors set to Never. The directory service agent (DSA) is hardcoded to try to backsync for up to 16 hours even if it is unable to do so.
WORKAROUND
To work around this problem, do one of the following:
- Make sure that the schedule on the connector of the remote Directory Replication Bridgehead is not set to Never. If it is, either set it to Always to allow for the proper delivery of directory replication messages, or wait for 16 or 4 hours respectively for this to time out.
-OR-
In Microsoft Exchange Server 5.0 SP1, it is possible to add a value to the registry that will control this timeout:
Under the HKEY_LOCAL_MACHINE subtree, add the value in minutes to the following subkey:
Key: System\CurrentControlSet\Services\MSExchangeDS\Parameters\ Value: Replicator inter site backsync timeout Data Type: REG_DWORD Value data: <number-of-minutes-in-hex>
The hex value of "f" equals 15 minutes in the line above.
This value is case-sensitive and must be entered as shown above.
STATUS
Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 4.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):
S E R V P A C K
Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):
S E R V P A C K
MORE INFORMATION
When a directory is restored from backup it attempts to get back -- backsync -- copies of all the objects which it last modifed or added which it replicated out to other computers since it was backed up. These computers can be in the same site or another site. Backsync is necessary becuase normally changes made at a DSA do not replicate back to that DSA, and also the Update Sequence Number (USN) for a restored computer will be lower than the USN it had before being restored. This means that if any changes are made at the restored computer before it has backsync'ed, they will not replicate out until the USN climbs to the value it was before the server was restored.
If the backsync is overridden by reducing the timeout, there is a risk of this replication loss. Therefore the backsync timeout should only be reduced or eliminated when you are sure that no changes were made at the restored computer since the computer was backed up."
Keywords: kbbug kbfix KB160850
