HP Xw6200 Hardware versus Software RAID on Linux Workstations - Page 3

Migration • Hardware RAID level migration tends to be much simpler than in software RAID. Availability • Since hardware RAID requires specific hardware drivers, it is not always available on Linux workstations as a certain hardware manufacturer may not provide Linux support. • Software RAID support is only available in kernel 2.4 and later. The RAID-6 level is only available on software RAID with the 2.6 kernel, whereas hardware RAID is available across all platforms. Simplicity • Software RAID has long been considered to be more complex to manage than hardware RAID. Software RAID exposes the management of each device to the user while hardware RAID uses logical block device representation. • Software RAID requires the user to understand the entire chain of reliances in the array, unlike hardware RAID which often has an "express" setup capability that requires far less understanding on the user's part. • Software RAID allows setup to be scripted, usually generically over many configurations. If configuration isn't available for a hardware RAID device, the manual configuration is often more difficult than with software RAID. Hardware Costs • Software RAID is almost always cheaper in terms of hardware because of the wider range of hardware choices in terms of disk drives and disk controllers, as well as not requiring the extra cost of the hardware RAID controller. Administrative Costs • Software RAID has higher administrative costs due to the exposed complexity of the RAID solution and the testing being migrated from vendor to user. • Hardware RAID offers more management features which reduce user administrative costs. Supportability • Hardware RAID offers higher levels of support and testing, but only on the specific configurations that have been supported by the hardware manufacturer. For this reason, hardware RAID controllers often restrict what devices can be used, while software RAID makes no assumptions about the components being used. • Software RAID also keeps the raw disks and partitions exposed so that server firmware and boot management can use them. Hardware RAID has the logical block device exposed so that it emulates common device geometry and behavior. Conclusion The primary reason for choosing hardware RAID over software RAID is that of convenience. Hardware RAID offers features to improve usability and ease of maintenance for users, whereas software RAID requires much more manual configuration. However, software RAID offers equal if not improved performance and greatly increased flexibility over hardware RAID. In the end, the decision between hardware and software RAID comes down to personal preference. Please see the HP Workstations User Manual for Linux for details on software RAID configuration. 3