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Table A-2 illustrates the differences between the different RAID levels.
0
2
Data striping without
redundancy
Highest performance
No data protection: if
one drive fails all data is
lost
1
2
Disk mirroring
Very high performance
and data protection;
minimal penalty on write
performance
High redundancy cost
overhead: because all
data is duplicated, twice
the storage capacity is
required
10
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
3
3
Block-level data striping
with dedicated parity
drive
Excellent performance
for large, sequential data
requests (fast read)
Not well-suited for
transaction-oriented
network applications:
single parity drive does
not support multiple,
concurrent write requests
5
3
Block-level data striping
with distributed parity
Best cost/performance
for transaction-oriented
networks; very high
performance and data
protection; supports
multiple simultaneous
reads and writes; can
also be optimized for
large, sequential requests
Write performance is
slower than RAID 0 or
RAID 1