Microsoft System Center Data Protection Manager (DPM) for Windows Server provides disk-to-disk short-term backup for data. DPM is not intended to replace tape or other long-term storage media, but it does offer a way to simplify and speed up most recovery operations.
To use Data Protection Manager, storage administrators must set up a storage pool to hold the replicas of data, transaction logs and other information. How well DPM performs in the enterprise depends on the size of the pool itself and on how competent administrators are at selecting a storage method for the data pool.
To estimate the size of the data pool, a storage admin should take the size of the protected data and add the daily shadow copy size times the number of days they want to store shadow copies of the data. Microsoft suggests starting with a disk pool two to three times the size of the protected data. This is based on two assumptions: that the daily shadow copy size will be about 10% of the protected data size and that you'll be retaining the shadow copies for 10 days.
Of course, both of these assumptions are likely to change as you gather more information on actual use. In particular, the daily shadow copy size may deviate significantly from the estimate. For that reason, Microsoft recommends making sure your storage arrays or other storage pool media are easy to expand.
Another consideration in designing the storage pool for DPM is how to store the data. DPM supports most forms of storage, including SANs and direct-attached storage (DAS) and most common storage technologies, including JBOD and RAID (but not 1394). So the choice of how to store the data inevitably comes down to economics and performance.
For the best combination of reliability and cost, Microsoft recommends RAID 5 for the storage data pool. However, even the company notes this is not an ideal solution, because RAID 5 has significant performance penalties on write operations and almost all disk activity on DPM is writing. RAID 10 offers better performance, but it requires much more disk capacity. Given the size of the storage pool, this can be economically prohibitive.
Microsoft has published a Microsoft System Center Data Protection Manager Planning and Deployment Guide
Microsoft System Center Data Protection Manager Fast Guide
Introduction
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 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.
