Selecting the Number of DPM Servers
Aplica-se a: System Center Data Protection Manager 2010
As you consider the number of DPM servers that your organization requires, keep in mind that there is no precise formula for determining the number of DPM servers. In practice, the number of servers and amount of data that a single DPM server can protect varies based on the following factors:
Change rate of the data sources to be protected
The amount of space available in the storage pool
How often the data will be synchronized
Available bandwidth at each protected computer
Aggregate bandwidth on the DPM server
To get an estimate of your data change rate, you can review an incremental backup for a recent, average day. The percentage of your data included in an incremental backup is usually indicative of your data change rate. For example, if you have a total of 100 GB of data and your incremental backup is 10 GB; your data change rate is likely to be approximately 10 percent per day.
However, because the method that DPM uses to record changes to data is different from that of most backup software, incremental backup size is not always a precise indicator of data change rate. To refine your estimate of your data change rate, consider the characteristics of the data you want to protect.
For example, while most backup software records data changes at the file level, DPM records changes at the byte level. Depending on the type of data that you want to protect, this can translate to a data change rate that is lower than the incremental backup might suggest.
The following table lists the data source limits that a DPM server that meets the minimum hardware requirements can protect and the recommended disk space required per DPM server.
| Platform | Data source limit | Recommended disk space |
|---|---|---|
64-bit computers |
300 data sources Data sources are typically spread across approximately 75 servers and 150 client computers. |
80 TB |
Snapshot Limit
A DPM server can store up to 9,000 disk-based snapshots, including those retained when you stop protection of a data source. The snapshot limit applies to express full backups and file recovery points, but not to incremental synchronizations.
The snapshot limit applies per DPM server, regardless of storage pool size. When you configure protection groups, the DPM server is provisioned for the number of snapshots to accommodate the protection group configuration. You can use the following cmdlet in DPM Management Shell to identify the number of snapshots for which the server is provisioned:
$server=Connect-DPMServer Name of the DPM server
$server.CurrentShadowCopyProvision
When planning your DPM deployment, consider the snapshot limit as part of the DPM server capacity. The following table lists examples of the number of snapshots that result from different protection policies.
| Protection policy | Snapshots |
|---|---|
Exchange storage group: daily express full backup and 15-minute incremental synchronization with a retention range of 5 days |
5 |
Volume on a file server: 3 daily recovery points with a retention range of 21 days |
63 |
SQL Server database: 2 express full backups daily with a retention range of 14 days |
28 |
Total: |
96 |