Specifications

Chapter 2 RAID Overview
19
♦ With the HP NetRAID-2M adapter, you can span up to eight RAID 5
arrays, although the total number of disks in the RAID 50 logical drive
is limited by the number of disks that can be attached to the two SCSI
channels. For example, if two Rack Storage/12 enclosures are used, the
maximum number of disks in a RAID 50 logical drive is 24.
RAID 50 gives good performance if you have a high volume of small, random
transfers.
RAID 50 Disadvantages
• Capacity expansion is an offline operation only.
• Performance is slower than RAID 0 or RAID 10.
RAID 50 Summary
• Choose RAID 50 if you need a large logical drive size, and cost, availability,
and performance are equally important. RAID 50 performs best for I/O-
intensive, high read/write ratio applications such as transaction processing.
Table 2-1. RAID Level Summary for RAID Levels 0 to 5
RAID Level RAID 0 RAID 1 RAID 5
Also Known As
striping mirroring striping with
distributed parity
Fault Tolerance
no yes yes
Redundancy Type
none duplicate parity
Hot Spare Option
no yes yes
Disks Required
one or more two three or more
Usable Capacity
greatest least intermediate
Capacity
Reduction
none 50% capacity of one disk
Read Performance
fast (depends on
number of disks)
intermediate fast
Random Write
Performance
fastest intermediate slow
Sequential Write
Performance
fastest intermediate slowest
Typical Usage
Rapid reads and
writes with no need
for fault tolerance
Mostly small
random writes with
fault tolerance
Mostly small,
random transfers
with fault tolerance