Table of Contents
Advertisement
MaxAttach NAS 6000 Administration Guide
RAID Level
RAID 5
Striping and parity distributed across ALL disks
Volume Set
No Striping No Parity
RAID Functional Comparison
The table below summarizes the strengths and limitations of each RAID and JOBD
configuration.
RAID
Description
Level
RAID 1
All data copied onto 2
separate disks
RAID 2
Data striped across
multiple disks with parity
on multiple disks
RAID 3
Data striped across all
data disks with
dedicated parity disk
RAID 4
Data striped across
some data disks with
dedicated parity disk
RAID 5
Data and parity striped
across multiple disks
*Write operations are slow in these cases because the controller must read parity information from a disk and recompute parity
information for the disk before it writes information to the disk array
Chapter #11 - Appendix - Disk Array RAID Concepts
11/07/01 -- Revision 2.0.03A
Table #1 - RAID Comparison
Description
Table #2 - RAID Level Comparison
Data
Data Transfer and
Reliability
I/O Request Rate
Very high.
Data transfer rate is higher than
Can withstand
single disk for reads, but does
selective multiple
not offer load balancing. Twice
disk failures
that of a single disk for reads.
Slightly slower than single disk
for writes
Very high.
High if error correcting codes are
Can withstand
computed by hardware Similar
selective multiple
to twice that of a single disk
disk failures
Much higher than
Highest of all types listed here
single disk.Can
for reading and writing Faster
withstand single
than a single disk, owing to
disk failure
parallel disk accesses
Much higher than
High compared to single disk for
single disk.
reads but significantly lower than
single disk for writes*.
Can withstand
single disk failure
Much higher than
High compared to single disk for
single disk.
read but generally lower than
single disk for writes*
Can withstand
Transaction processing with high
single disk failure
read to write ratio.
264
Chapter #11 - Appendix - Disk Array RAID Concepts
RAID Functional Comparison
I/O
Advantage
Tolerance
YES
NO
Application
Strength
General
General
Video, prepress,
medical imaging,
and other large file
applications
Predominantly
read-oriented with
few writes
Low. Requires only
one disk for
redundancy
Fault
YES
NO
Cost
Very high.
Requires twice
as many disks
for redundancy
High. Requires
multiple disks
for redundancy
Low. Requires
only one disk
for redundancy
Low.
000001628
Advertisement
Table of Contents
