LaCie 5big network User Manual

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LaCie 5big network User Manual Manual pdf 54 page image

LaCie 5big network RAID and DisksUser Manual page 54RAID 105.6.RAID 10 (also called RAID 1+0) is another RAID level that com-bines the attributes of other levels, specifically RAID 1 and RAID0. It is a “stripe of mirrored sets”, meaning that data is stripedacross two mirrored arrays. The Striping occurs between arraysand the mirroring occurs within the same array, which makesthe rebuilding very fast. RAID 10 arrays should have disks inmultiples of four. For LaCie products with five disks, in a RAID10 array, the fifth disk will either be a spare or will be unused.See the diagram at right.In a RAID 10 array, one disk from each mirrored pair can failwith no data loss. However, the working disk in an array with afailed disk becomes a weak point for the entire array. If the sec-ond disk in a mirrored pair fails, the entire array is lost.ApplicationsRAID 10 provides good speeds because of RAID 0 striping, butcuts the available capacity of a device in half (assuming all disksin the array have the same capacity).How RAID 10 Capacity Is CalculatedEach disk in a RAID 10 system should have the same capacity.Storage capacity in a RAID 10 configuration is calculated by mul-tiplying the number of drives by the disk capacity and dividing by2, orC = n*d/2where:C = available capacityn = number of disksd = disk capacityFor example, in a RAID 10 array with four drives each with acapacity of 1000GB, the total capacity of the array would be2000GB:C = (4*1000)/2RAID 1 RAID 1RAID 0A2A4A6A8RAID 10A2A6A8A4A1A3A7A5A1A3A5A7Disk 1 Disk 2 Disk 3 Disk 4