EMC CX500I Configuration Guide - Page 38

RAID Types and Trade-offs With a RAID 1 mirrored pair, the storage system writes the same data to both disks, as follows. First Disk 0 1 2 3 4 ... Second Disk 0 1 2 3 4 ... User Data EMC1817 Figure 2-4 RAID 1 Mirrored Pair RAID 1/0 Group (Mirrored RAID 0 Group) A RAID 1/0 Group consists of four, six, eight, ten, twelve, fourteen, or sixteen disks. These disks make up two mirror images, with each image including two to eight disks. The hardware automatically mirrors the disks. A RAID 1/0 Group uses disk striping. It combines the speed advantage of RAID 0 (Page 2-10) with the redundancy advantage of mirroring. With a RAID 1/0 Group, you can create up to 128 RAID 1/0 LUNs to apportion disk space to different users, servers, and applications. Figure 2-5 shows the distribution of user data with the default stripe element size of 128 sectors (65,536 bytes) in a six-disk RAID 1/0 Group. Notice that the disk block addresses in the stripe proceed sequentially from the first mirrored disks (first and fourth disks) to the second mirrored disks (second and fifth disks), to the third mirrored disks (third and sixth disks), and then from the first mirrored disks, and so on. 2-8 EMC CLARiiON CX300, CX500, CX500i, and CX700 Storage Systems Configuration Planning Guide