Microsoft System Center Data Protection Manager (DPM) keeps track of the amount of storage it is using for replica and shadow copies. When usage exceeds 75%, it warns you with a message saying "disk threshold exceeded."
That's nice, but you should never get the warning message. Sure, the warning lets you add storage space before the situation becomes critical, but what it really indicates is that you need to look at the Data Protection Manager parameters to figure out why DPM is gobbling storage space.
When DPM initializes, it automatically sets storage requirements based on algorithms that predict how much storage space it will need. The resulting estimates are generous and should suffice, since DPM data is rolled off the Data Protection Manager server after a period of time. (As a recent SearchWinComputing.com tip discussed, Microsoft System Center Data Protection Manager is not a complete backup solution.)
According to Microsoft, the problem is that you're running through storage faster than DPM expects. And there are two reasons why this is happening: Either data is growing too fast or the files are changing too fast.
If it's the former, it means the protected data on the source volume has outgrown the parameters Data Protection Manager set on initialization. There is more data to protect and so there is no longer enough space allocated.
DPM's storage estimates assume that the files being protected will change at a certain rate. So if the rate of change is higher than expected, the shadow copies will be larger and Microsoft System Center Data Protection Manager will need more storage space for them.
In each case the solution is to add more storage to the storage pool for Data Protection Manager amount of storage allocated to DPM or, if there is not enough space available, by adding one or more disks to the Microsoft System Center Data Protection Manager server.
Microsoft discusses this situation in greater detail in this TechNet article.
Microsoft System Center Data Protection Manager Fast Guide
Verifying Data Protection Manager status
Server plays key role in Data Protection Manager deployment
Why Data Protection Manager is replacing disk-to-tape backups
Troubleshooting Data Protection Manager warning message
Measuring the impact of Data Protection Manager 2006
Storage pool savvy helps admins optimize Data Protection Manager
Watch out for unsupported data types in Data Protection Manager
Protecting servers with Data Protection Manager
About the Author:
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last 20 years he has been a freelance writer specializing in issues related to storage and storage management.