RAID Level
Minimum disk
Maximum disk
10
4
240
50
6
240
60
8
240
NOTE:
Maximum number of virtual disks is currently limited to 192, because of the supported enclosure configuration.
RAID terminology
Disk striping
Disk striping allows you to write data across multiple physical disks instead of just one physical disk. Disk striping involves partitioning each
physical disk storage space in stripes of the following sizes: 64 KB, 128 KB, 256 KB, 512 KB, and 1 MB. The stripes are interleaved in a
repeated sequential manner. The part of the stripe on a single physical disk is called a stripe element.
For example, in a four-disk system using only disk striping (used in RAID 0), segment 1 is written to disk 1, segment 2 is written to disk 2,
and so on. Disk striping enhances performance because multiple physical disks are accessed simultaneously, but disk striping does not
provide data redundancy.
Figure 13. Example of disk striping (RAID 0)
Disk mirroring
With mirroring (used in RAID 1), data written to one disk is simultaneously written to another disk. If one disk fails, the contents of the other
disk can be used to run the system and rebuild the failed physical disk. The primary advantage of disk mirroring is that it provides complete
data redundancy. Both disks contain the same data at all times. Either of the physical disks can act as the operational physical disk.
Disk mirroring provides complete redundancy, but is an expensive option because each physical disk in the system must be duplicated.
NOTE:
Mirrored physical disks improve read performance by read load balance.
Figure 14. Example of Disk Mirroring (RAID 1)
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Appendix RAID description
