HP StorageWorks 2000 Modular Smart Array Reference Guide (481599-003, August 2008)

252 HP StorageWorks 2000 Family Modular Smart Array reference guide • August 2008
Comparing RAID Levels
Table A-2 illustrates the differences between the different RAID levels.
Table B-2 RAID Level Comparison
RAID
Level
Min.
Number
of Drives Description Strengths Weaknesses
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