HP P2000 HP P2000 G3 MSA System SMU Reference Guide - Page 31

About size representations, RAID level, Expansion capability, Maximum disks, level, disks, Description

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Table 5 RAID level comparison (continued) RAID level 5 6 10 (1+0) 50 (5+0) Min. Description disks 3 Block-level data striping with distributed parity 4 Block-level data striping with double distributed parity 4 Stripes data across multiple RAID-1 sub-vdisks 6 Stripes data across multiple RAID-5 sub-vdisks Strengths Weaknesses 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; protects against single disk failure Write performance is slower than RAID 0 or RAID 1 Best suited for large sequential workloads; non-sequential read and sequential read/write performance is comparable to RAID 5; protects against dual disk failure Higher redundancy cost than RAID 5 because the parity overhead is twice that of RAID 5; not well-suited for transaction-oriented network applications; non-sequential write performance is slower than RAID 5 Highest performance and data protection (protects against multiple disk failures) High redundancy cost overhead: because all data is duplicated, twice the storage capacity is required; requires minimum of four disks Better random read and write performance and data protection than RAID 5; supports more disks than RAID 5; protects against multiple disk failures Lower storage capacity than RAID 5 Table 6 Vdisk expansion by RAID level RAID level Expansion capability Maximum disks NRAID Cannot expand. 1 0, 3, 5, 6 You can add 1-4 disks at a time. 16 1 Cannot expand. 2 10 You can add 2 or 4 disks at a time. 16 50 You can add one sub-vdisk at a time. The added sub-vdisk must contain the same 32 number of disks as each of the existing sub-vdisks. About size representations Parameters such as names of users and volumes have a maximum length in bytes. ASCII characters are 1 byte; most Latin (Western European) characters with diacritics are 2 bytes; most Asian characters are 3 bytes. Operating systems usually show volume size in base 2. Disk drives usually show size in base 10. Memory (RAM and ROM) size is always shown in base 2. In SMU, the base for entry and display of storage-space sizes can be set per user or per session. When entering storage-space sizes only, either base-2 or base-10 units can be specified. HP P2000 G3 MSA System SMU Reference Guide 31

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HP P2000 G3 MSA System SMU Reference Guide
31
About size representations
Parameters such as names of users and volumes have a maximum length in bytes. ASCII characters are 1
byte; most Latin (Western European) characters with diacritics are 2 bytes; most Asian characters are 3
bytes.
Operating systems usually show volume size in base 2. Disk drives usually show size in base 10. Memory
(RAM and ROM) size is always shown in base 2. In SMU, the base for entry and display of storage-space
sizes can be set per user or per session. When entering storage-space sizes only, either base-2 or base-10
units can be specified.
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; protects
against single disk failure
Write performance is slower than
RAID 0 or RAID 1
6
4
Block-level data striping
with double distributed
parity
Best suited for large sequential
workloads; non-sequential read
and sequential read/write
performance is comparable to
RAID 5; protects against dual disk
failure
Higher redundancy cost than
RAID 5 because the parity
overhead is twice that of RAID 5;
not well-suited for
transaction-oriented network
applications; non-sequential write
performance is slower than RAID
5
10
(1+0)
4
Stripes data across
multiple RAID-1
sub-vdisks
Highest performance and data
protection (protects against
multiple disk failures)
High redundancy cost overhead:
because all data is duplicated,
twice the storage capacity is
required; requires minimum of four
disks
50
(5+0)
6
Stripes data across
multiple RAID-5
sub-vdisks
Better random read and write
performance and data protection
than RAID 5; supports more disks
than RAID 5; protects against
multiple disk failures
Lower storage capacity than RAID
5
Table 6
Vdisk expansion by RAID level
RAID level
Expansion capability
Maximum disks
NRAID
Cannot expand.
1
0, 3, 5, 6
You can add 1–4 disks at a time.
16
1
Cannot expand.
2
10
You can add 2 or 4 disks at a time.
16
50
You can add one sub-vdisk at a time. The added sub-vdisk must contain the same
number of disks as each of the existing sub-vdisks.
32
Table 5
RAID level comparison (continued)
RAID
level
Min.
disks
Description
Strengths
Weaknesses