Introduction to RAID technology 4.3.3 Distributed RAID In distributed RAID, all drives are active, which improves performance. Spare capacity is used  instead of the idle spare drives from traditional RAID. Because no drives are spare, all drives  contribute to performance. The spare capacity is rotated across the disk drives so the write  rebuild load is distributed across multiple drives and the bottleneck of one drive is removed. Figure 4-47 on page 197 shows an example of a distributed RAID with 10 disks. The physical  disk drives are divided into multiple packs. The reserved spare capacity (which is marked in  yellow) is equivalent to two spare drives, but the capacity is distributed across all of the  physical disk drives.  Note:  Although Traditional RAID is still supported and is the default choice in the GUI, the  suggestion is to use DRAID 6 whenever possible. It depends on the number of disk drives,  type, and size. When multiple physical disks are set up to use the RAID technology, they are in a  RAID array .  The IBM Storwize V5000 Gen2 provides the following traditional RAID levels: RAID provides two key design goals: RAID technology can provide better performance for data access, high availability for the  data, or a combination. RAID levels define a trade-off between high availability, performance,  and cost. The RAID concept must be extended to  disk rebuild time  because of increasing physical disk  capacity.  In a disk failure, traditional RAID writes the data to a single spare drive. With increasing  capacity, the rebuild time is also increased and the probability of a second failure during the  rebuild process becomes more likely. In addition, the spares are idle when they are not being  used, which wastes resources. Distributed RAID (DRAID) addresses these points and is available for the IBM Storwize  V5000 Gen2 in two types:  Distributed RAID reduces the recovery time and the probability of a second failure during  rebuild. As with traditional RAID, a distributed RAID 5 array can lose one physical drive and  survive. If another drive fails in the same array before the bad drive is recovered, the MDisk  and the storage pool go offline as they are supposed to. So, distributed RAID does not  change the general RAID behavior.  196  Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.2.1 GLYPH<SM590000> Distributed RAID 6 (DRAID 6) GLYPH<SM590000> Distributed RAID 5 (DRAID 5) GLYPH<SM590000> RAID 10 GLYPH<SM590000> RAID 6  GLYPH<SM590000> RAID 5 GLYPH<SM590000> RAID 1 GLYPH<SM590000> RAID 0 GLYPH<SM590000> Increased input/output (I/O) performance  GLYPH<SM590000> Increased data reliability