Lacie 4big Quadra User Manual - Page 15

LaCie 4big Quadra Enterprise Class • Design by Neil Poulton User Manual RAID page 15 3.1.2. RAID 10 RAID 10 (also called RAID 1+0) is another RAID level that combines the attributes of other levels, specifically RAID 1 and RAID 0. It is a "mirror of stripes", meaning that data is striped across two mirrored arrays. The Striping occurs between arrays and the mirroring occurs within the same array. See Fig. 08. In a RAID 10 array, one disk from each mirrored pair can fail with no data loss. However, the working disk in an array with a failed disk becomes a weak point for the entire array. If the second disk in a mirrored pair fails, the entire array is lost. Applications RAID 10 provides good speeds because of RAID 0 striping, but cuts the available capacity of a device in half (assume all disks in the array have the same capacity). 3.1.3. Concatenation When disks are concatenated, their capacities are combined and data is written to the primary disk in the array until is it full, and then to successive disks (Fig. 09). Concatenation provides no performance advantage or added measure of data safety. It is simply a method of combining more than one physical disk into one volume for greater overall capacity. Concatenation allows full use of the capacity of all disks in the array and most data can survive a disk failure. Only data on the failed disk and data that is partially written on the failed disk and an operative disk is lost. Offers the maximum possible capacity by combining the capacities of several drives into one large volume. RAID 10 RAID 0 RAID 1 A1 A3 A5 A7 Disk 1 Fig. 08 A1 A3 A5 A7 Disk 2 RAID 1 A2 A4 A6 A8 Disk 3 A2 A4 A6 A8 Disk 4 Concatenation A B C D Disk 1 Fig. 09 E F G H Disk 2 I J K L Disk 3 M N O P Disk 4