- G- and K-Series External RAID Board Controller User's Guide

G- and K-Series User’s Guide
A-4
Volume Sets
A volume set is the ability to create a host-accessible LUN that maps to a single disk
in the array, similar to JBOD. Volume sets are non-redundant and have a capacity
slightly less than the physical disk they are created from. Volume sets are useful if you
have a single disk available and you don’t want to use it as a spare.
Note:
For more information on RAID levels, see
The RAIDbook: A Source
Book for RAID Technology, published by the RAID Advisory Board (St.
Peter, Minnesota: February, 1996).
Comparing RAID Levels
Table A-1 illustrates the differences between the different RAID levels:
Table A-1. Comparing RAID Levels
RAID
Level
Min No.
of Drives Description Strengths Weaknesses
RAID 0 2 Data striping
without
redundancy
Highest
performance
No data
protection—one
drive fails, all data
is lost
RAID 1 2 Disk mirroring Very high:
• Performance
• Data protection
• Minimal penalty
on write
performance
High redundancy
cost overhead—
because all data is
duplicated, twice
the storage
capacity is required
RAID 2 n/a No practical use Previously used for
RAM error
environments
correction (known
as Hamming Code)
and in disk drives
before the use of
embedded error
correction
No practical use—
same performance
can be achieved by
RAID 3 at lower
cost