| The synthetic time problem is one the Novell Product Support forums see more often than any other problem. Unfortunately, in many cases, the advice given to users does not include the first few steps necessary to determine whether simply waiting is a viable option for the problem to resolve itself. This is a case where waiting is the best alternative. Synthetic time occurs when the modification timestamp (MTS) on at least one object in the partition is set to a time that is in the future, according to the real-time clock on the server reporting the problem. Because a single object can cause the error, it is important that you find out how far ahead the MTS is and base your solution on that information. DSRepair can tell you this when you run either an unattended full repair or a local database repair. Objects with future MTSs are reported in the log file as shown here: ERROR: Illegal timestamps were found in this replica. You may need to run the advanced option: 'Repair timestamps and declare new epoch' Value: 4054e3cb, ID: 00008059, DN: T=W2K-873-TEST-TREE 03/14/2010 05:59:23 PM; rep # = 0001; event = 0001
The last line here shows the MTS to be many years in the future. The way this problem is corrected depends on how far ahead the MTS is. If it is measurable in days, you can simply wait for the time to catch up. Synthetic time ensures that the future MTS and the current real-time converge. This convergence typically takes half the time of the difference between the future timestamp and the current time. So if the MTS is reported to be an hour into the future, it should take about 30 minutes for the problem to resolve itself. If, however, the time differential is measurable in months or years (as the preceding example shows), we recommend that you repair the timestamps. Table 11.4 outlines the procedure that must be repeated for each replica stored on the server that has one or more objects with a future MTS. Table 11.4. Procedures for Repairing Each Timestamp | OPERATING SYSTEM | PROCEDURE | | NetWare | Load DSREPAIR.NLM with the -A switch. Select Advanced Options, Replica and Partition Operations. Highlight a replica and press Enter. Select Repair Time Stamps and Declare a New Epoch (see Figure 11.17). Figure 11.17. The Repair Time Stamps and Declare a New Epoch option in DSRepair. 
| | Windows | Start dsrepair.dlm with the -A switch. Expand the Partitions list, righ t-click a replica, and select Repair Time Stamps and Declare a New Epoch (see Figure 11.17). | | Linux/Unix | Run ndsrepair -P -Ad . Select a replica and then select Replica Options, Repair Time Stamps and Declare a New Epoch. |
When the Repair Time Stamps and Declare a New Epoch option is selected, you are prompted for a user login and password. The login ID you use here must have Supervisor rights to the portion of the tree where the timestamp repair is taking place. WARNING Repairing timestamps is a very traffic- intensive operation because all non-Master replicas of the partition are essentially destroyed and re-created. This can cause loss of services that require bindery contexts for the duration of the repair. Depending on the number of replicas and their sizes, this operation can take hours to complete. You should make sure to schedule time off-hours to perform this operation if it is necessary.
When this operation is initiated, you must wait for it to complete before issuing a second timestamp repair. If the server has multiple replicas with future timestamps, you need to wait for each repair to complete before starting the next one; if you don't, you might flood other servers on the network with too much traffic and introduce further problems. Because this operation destroys replicas on non-Master replica servers, you need to make sure you minimize the number of changes taking place from one repair to the next . You should run the first repair and verify that it has completed (all replicas should show an On state in DSRepair or NDS iMonitor when the repair is complete) before initiating another ”even if the other is in a different part of the tree. | 