The Sun Blade Server Module supports two types of array architectures: RAID-0 and RAID-1. By default, Sun-supplied disk drives are shipped without a hardware RAID configuration. Before installing Linux, you must decide whether you want to configure a hardware RAID, and if so, which type of hardware RAID configuration you want to implement. A brief description about hardware RAID and the two hardware RAID levels supported on Sun-supplied disk drives follows.
A hardware RAID configuration enables you to combine multiple small disk drives into an array of disk drives that yields performance, capacity, and/or reliability in excess of that provided by a single disk drive. Additionally, the RAID volume appears to the server as a single logical storage unit or drive.
One of the factors you should consider if you decide to configure hardware RAID is the reliability Mean Time Between Failure (MTBF). The MTBF of a RAID-0 array is equal to the MTBF of a single drive, divided by the number of drives in your array. For many applications, this MTBF could be too low. In this situation, you may want to consider configuring your disk array to support fault-tolerance. A fault-tolerant disk array (RAID-1) enables you to redundantly mirror the information on two duplicate disks simultaneously. If one disk fails, the server can instantly switch to the other disk without any loss of data or service.
A second factor you should consider when configuring a hardware RAID is disk access and performance. Data striping distributes the data across multiple disks to increase throughput and the effective disk size. The performance increase depends on the application. When using this level of RAID, you are trading performance for reliability since there is no redundancy or fault tolerance. If either disk in the RAID-0 pair should fail, the whole RAID fails.
Based on the first and second factors discussed previously, you will need to decide which of the two supported hardware RAID levels to implement:
Level-0 = Striped Disk Array Without Fault Tolerance (IS Volume). Note that in the LSI Logic Configuration Utility, Level-0 is known in the BIOS as IS Volume.
Level-1 = Mirroring (IM Volume). Note that in the LSI Logic Configuration Utility, Level-1 is known in the BIOS as IM Volume.
If you have decided to implement a hardware RAID on a Sun-supplied hard disk drive (SAS or SATA HDD), instructions for configuring a hardware RAID are provided later in Configuring Hardware RAID (Optional).