LaCie 5big Network 2 User Manual

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LaCie 5big Network 2 User Manual Manual pdf 54 page image

LaCie 5big Network 2 • DESIGN BY NEIL POULTON Administering Your LaCie 5big Network 2User Manual page 544.17.2. About RAID ModesRefer to the table below for an overview of the different RAID modes,and see the descriptions for details.RAID Mode Capacity ProtectionRAID 5 (default) 80%RAID 5+Spare 60%RAID 6 60%RAID 10* 50%RAID 0 100%RAID 1** 50%RAID5: In RAID 5, data is striped across all disks (minimum of three)and a parity block for each data block (P in Fig. 78) is written on thesame stripe. If one physical disk fails, the data from the failed diskcan be rebuilt onto a replacement disk. No data is lost in the caseof a single disk failure, but if a second disk fails before data can berebuilt to a replacement drive, all data in the array will be lost.RAID5+Spare: RAID 5+Spare is a RAID 5 array in which one disk isused as spare to rebuild the system as soon as a disk fails (Fig. 79).At least four disks are required. If one physical disk fails, the dataremains available because it is read from the parity blocks. Datafrom a failed disk is rebuilt onto the hot spare disk. When a faileddisk is replaced, the replacement becomes the new hot spare. Nodata is lost in the case of a single disk failure, but if a second diskfails before the system can rebuild data to the hot spare, all data inthe array will be lost.RAID6: In RAID 6, data is striped across all disks (minimum of four)and a two parity blocks for each data block (p and q in Fig. 80) iswritten on the same stripe. If one physical disk fails, the data fromthe failed disk can be rebuilt onto a replacement disk. This Raidmode can support up to two disk failures with no data loss. RAID 6provides for faster rebuilding of data from a failed disk.continued on the next page >>Fig. 78Fig. 79K:B=.Disk 1 Disk 2 Disk 3 Disk 4 Disk 5A2B2D1CpA1B1C1D1EpA2B2C2DpE1A3C2D2Bp B3C3D3A3B3CpD2E2A4BpC3D3E3ApB4C4D4E4K:B=.$LiZk^Disk 1 Disk 2 Disk 3 Disk 4 Disk 5B2D1CpA1B1C1DPA3C2D2Bp B3A3D2ApC3D3SpareA2Fig. 80K:B=/Disk 1 Disk 2 Disk 3 Disk 4 Disk 5ApBqC3D3AqB3C3D3A3CqD2BpA2B2DqCpA1B1C1Dp* RAID 10 is only available if there are four disks installed in the 5big Net-work 2.** RAID 1 is only available if there are two disks installed in the 5big Network2.