Continuing a thread from DPM General Forum where it was suggested to continue the conversation in the Windows Server open forum. Recap - All Products, drivers, firmware, etc are up to date. DPM 2010 (running on 2008 R2 SP1) is installed on two different HP DL 180 G6s with locally attached storage arrays (the secondary DPM server has a second drive array SAS attached VIA a MSA60 for another 20TB array). DPM 2010 is protecting 3 clustered SIS volumes on a Clustered 2008 Small Storage Server. All three volumes are SIS enabled, and all 3 of the protected volumes have replicated to the DPM servers. First Primary, then Secondary. Beyond deleting, and recreating the replicas (which has been done) In attempts to rule out the Primary DPM Server itself, the Secondary DPM Server has been put in to DR - Switched Protection. Where upon the problem of a 'missing volume' follows to the second server. No system logs, VSS errors, NTFS disk errors etc are noted in either the DPM server or protected servers logs. What I found this morning, is that the 'missing volume' is not displaying its volume label, and that is the only other symptom I have been able to find. Mountvol shows the replica volume, and indeed when there are no synchronization or other DPM jobs running, I can mount the replica volume and browse to the data. Yet, DPM 2010 keeps coming up with a random Missing Volume error, and subsequently stops running jobs temporarily. Then later, of its own accord, starts successfully running jobs once it has been able to detect the volume. So, DPM is protecting 3 sources from the same cluster, which means DPM generated 6 local volumes on my disk array, and only 1 of them is being marked Missing. Also, this behavior followed from one DPM server to the next. What could cause this, or the following 'missing label' in the below screen shot?