YhdistelmäRAIDtasot

YhdistelmäRAIDtasot, often referred to as nested or hybrid RAID levels, combine the advantages of two or more basic RAID levels to offer improved performance, reliability, or capacity. These levels are constructed by grouping multiple disks into a standard RAID array and then creating another RAID array from these initial arrays. This layering allows for the benefits of both constituent RAID levels to be leveraged.

The most common combined RAID levels are RAID 10 (or RAID 1+0) and RAID 01 (or RAID 0+1). RAID 10 stripes data across mirrored pairs of disks. This provides the redundancy of mirroring and the performance benefits of striping. If a drive fails in a mirrored pair, the array continues to function using the remaining drive in that pair. RAID 01, conversely, mirrors entire striped sets. While offering similar redundancy and performance, RAID 01 is generally considered less resilient than RAID 10. In RAID 01, if one drive fails in a striped set, the entire mirrored set is lost, whereas in RAID 10, only one drive in a pair is lost.

Other less common combined RAID levels exist, such as RAID 50 (RAID 5+0) and RAID 60 (RAID 6+0). RAID 50 stripes data across multiple RAID 5 arrays, offering a balance of performance, capacity, and fault tolerance. RAID 60 stripes data across multiple RAID 6 arrays, providing even higher levels of fault tolerance due to the double parity of RAID 6. The choice of combined RAID level depends on the specific requirements for data availability, read/write performance, and acceptable cost.

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