DataDirect Networks EF2800, User Manual

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A r r a y B a s i c s
DataDirect Networks EF2800 FC RAID Storage System User Guide (V 1.0)
191
B.3 Mixing Disks from Different Manufacturers/
Capacities
An array can contain disks with different capacities; for example, an
array can include a 36-GB disk and a 72-GB disk. If you mix disks with
different capacities, the smallest disk determines the logical capacity of
all other disks in the array, regardless of RAID level. For example, if a
RAID 0 array contains one 36-GB disk and four 72-GB disks, the
capacity of the array is equivalent to approximately five 36-GB disks. To
maximize disk capacity, use disks of similar size.
NOTE: The manufacturer does not support mixing of different models,
or manufacturer’s, of drives in the same enclosure.
RAID 50 6 Combination of
RAID 0 (data
striping) and
RAID 5 with
distributed
parity Better random
performance and data
protection than RAID
5; supports more
drives than RAID 5 Lower storage
capacity than RAID 5
RAID 10
(Also
known as
mirrored)
4 Combination of
RAID 0 (data
striping) and
RAID 1
(mirroring) Highest performance
and data protection
(can tolerate multiple
drive failures) High redundancy cost
overhead; because all
data is duplicated,
twice the storage
capacity is required;
requires minimum of
four drives
Volume
Sets
1 Non-RAID, non-
striped mapping
to a single drive
(similar to JBOD) Ability to use a single
drive to store
additional data Not protected, lower
performance (not
striped)
Figure 76. RAID Levels Comparison
RAID Level
Min. # of
Drives
Description Strengths Weakness