The Different Raid Levels - ICP RS Series User Manual

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C.2.1 The Different RAID Levels
RAID 0 - Data Striping
According to the adjusted stripe size (e.g., 128 KB) and the number of hard disks, the data
blocks are split into stripes. Each stripe is stored on a separate hard disk. Especially with
sequential read and write operations, we can observe a significant improvement of the data
throughput. RAID 0 includes no redundancy at all, i.e., when one hard disk fails, all data is
lost.
RAID 1 - Disk Mirroring/Disk Duplexing
All data is stored twice on two identical hard disks. When one hard disk fails, all data are
immediately available on the other without any impact on the performance and data integ-
rity.
We talk about "Disk Mirroring" when two hard disks are mirrored on one I/O channel. If each
hard disk is connected with a separate I/O channel, this is called "Disk Duplexing"
(additional security).
RAID 1 represents an easy and highly efficient solution for data security and system avail-
ability. It is especially suitable for installations which are not too large (the capacity avail-
able is only half of the installed capacity).