Planning the Disk Configuration

Published : April 8, 2005 | Updated : August 17, 2005

If you are using direct-attached storage for the storage pool, you can use any hardware-based configuration of redundant array of independent disks (RAID), or you can use a “just a bunch of disks” (JBOD) configuration. DPM does not support software-based configurations of RAID.

To decide on the configuration for the disks, consider the relative importance of capacity, cost, reliability, and performance in your environment. For example, because JBOD does not consume disk space for storing parity data, a JBOD configuration makes maximum use of storage capacity. For the same reason, the reliability of JBOD configurations is poor; a single disk failure inevitably results in data loss.

For the typical DPM deployment, a RAID 5 configuration offers an effective compromise between capacity, cost, reliability, and performance. However, because the DPM server workload is composed primarily of write operations, RAID 5 is likely to degrade the performance of a DPM server more markedly than it would in the case of a file server. This degradation in performance can in turn affect the scalability of DPM. The ability of DPM to effectively protect data degrades as performance degrades.

To help you evaluate options for configuring the disks in your storage pool, Table 2.5 compares the trade-offs between JBOD and the various levels of RAID, on a scale from (very good) to (acceptable).

Table 2.5   Comparison of Configuration Options for Storage Pool Disks

Disk Configuration




Performance and Scalability


























For more information about RAID, see Achieving Fault Tolerance by Using RAID (