G-Technology G-RACK 12, User Manual

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appendices
p. 295
Appendix. RAID levels explained
RAID stands for “Redundant Array of Independent Disks” and was first used in 1988. RAID technology
was developed to improve data protection and performance, while storing large amounts of data.
It allows to group multiple physical disks into a logical drive and apply one the existing RAID levels.
Depending on the RAID level selected, performance, redundancy, storage capacity and reliability of
the logical drive will differ. Most levels offer redundancy against drive failure.
There are several RAID levels or configurations that are defined and standardized upon and also
some of the hybrid RAID configurations.
RAID Level Description Advantage Drawbacks Ideal For
JBOD
Just-a-bunch-of-
disks
Each drive can be ac-
cessed as an individ-
ual volume. Usable
storage capacity is
100% of total avail-
able storage
No fault tolerance Audio applications
RAID 0 Disk striping
Offers the highest
performance and a
100% of total avail-
able storage capacity No fault tolerance
- failure of one drive
in the array results in
complete data loss Content creation ap-
plications requiring
highest performance
and storage capacity
RAID 1 Mirroring
Maximum level of
data protection:
identical data is writ-
ten to multiple drives
Usable storage space
is 50% of total avail-
able space Applications in which
data security is para-
mount
RAID 3
Data striped in bytes
across multiple
drives. Dedicated
parity drive
High sustained data
transfer rate. No
performance deg-
radation after drive
failure.
Redundancy
Lower performance
with small, random
requests
Performance- driven
applications with
large sequential
blocks of data