Technical information

About This DIGITAL HiTest Suite
2–4
HiTest Notes for Lotus Domino Windows NT Prioris MX
Figure 2-1: RAID Level Summary
RAID Level
0
1
2
3
4
5
Stripin
g
- Nonredundant
Mirrorin
g
B
y
te Interleaved, ECC
B
y
te Interleaved, Parit
y
Block Interleaved, Parit
y
Block Interleaved,
Distributed Parit
y
ML014332
DIGITAL and other companies also use the terms RAID 0+1, RAID 1+5 and Adaptive 3/5 to
refer to the combinations of these, and other, storage technologies. Table 2-2 describes the
RAID types to consider when choosing a RAID configuration.
Table 2-2: RAID Levels and Descriptions
RAID
Level
Description Advantages/Disadvantages
0
•
Striping
•
Data segmented and
distributed across several
disks
+ increase in performance due to parallelism in
read and write
- no fault tolerance (
not
a high availability
solution)
1
•
Hardware Mirroring
•
Data written twice to different
disk spindles within the disk
array
+ good performance in read-intensive
applications (data can be read in parallel from
several disks)
- slower in writes (multiple writes required)
- spindle costs doubled
0+1
•
Striped Mirroring
•
Combined level 0 and 1
•
Data mirrored onto and
striped across several disks
•
Best for performance-critical,
fault-tolerant environments
+ good performance in reads (RAID 1)
+ write performance improved versus RAID 1
due to parallelism
+ adequate response maintained in event of disk
failure
- spindle costs doubled
- recovery is I/O intensive
2
•
Parallel access array
•
Striped
•
ECC on separate drives
+ high data transfer rate
+ ECC detects and corrects errors
- low I/O request rate
- not appropriate with modern drives