dpm 2007 sp1 backup exchange failed with “discontinuity in the log chain”

I get a dpm 2007 sp1 backup exchange failed error today. like below:

The following alert occurred at 3/26/2010 11:17:33 AM.
Status: Active
Description: Backup to tape failed. 
DPM has detected a discontinuity in the log chain for SL-SG-102 on 
MAIL-102.MAIL-120.xunyang.ad since the last synchronization. 
For more information, open DPM Administrator Console and review the alert 
details in the Monitoring task area.

this error is a “ as is ”. it means that the logs is not a full chain, some of the log on the chain is broken or something else that can not be verified by the DPM backup process.  And of course this is a exchange related error not the dpm’s issue. The simple solution is move logs that you think maybe broken from origenal path to another path, then try backup again. I suggest you move non-today logs first. after the backup successful, it is fine to remove those backup logs.