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5-6 Intel® Server RAID Controller U3-1 User’s Manual Rev 1.0
RAID Features
5.2 Overview of the RAID Subsystem
5.2.1 Summary of RAID Levels
SRCU31 supports RAID Levels 0,1, 5 and 10. Table 5-1 provides a summary of RAID levels.
Table 5-1. Summary of RAID Levels
Intel® Server RAID Controller U3-1 Features and Performance
RAID
Level
Description
Minimum
Numberof
Drives
Supported
Maximum
Number of
Drives
Supported
Data
Reliability
(protection)
Data
Transfer
Rates
Relative
I/O Rates
0
Striping of data across
multiple drives in an array.
This is a high performance
solution, however there is
no data protection.
115
No data
protection.
Very High
Veryhigh for
both reads
and writes.
1
Also known as mirroring.
Mirroring refers to the
100% duplication of data
from one disk to another.
This is a high availability
solution, but due to the
100% duplication, it is also
a costly solution.
22
Highest
reliability;
much higher
reliability than
a single drive
(no RAID).
Reads are
higher than
a single
drive.
Writes are
about the
same as a
single drive.
Reads are
up to two
times faster
thanasingle
drive.
Writes are
about the
same as a
single drive.
5
Striping with parity. Data
and parity information is
spread among each drive
in the drive group. Parity is
equal to the total number
of disks in the volume
minus one drive. That one
drive must be equal to the
smallest drive capacity in
the array.
315
Lower
reliability than
RAID 1;
higher
reliability than
a single drive
or RAID 0.
Reads are
similar to
RAID 0.
Writes are
slower than
a single
drive due to
penalty of
writing
parity.
Reads are
similar to
RAID 0.
Writes are
usually
slower than
a single
drive.
10
RAID 10 is a combination
of RAID 0 and RAID 1.
This feature is not user
selectable. It is a function
of how Intel® Server RAID
Controller U3-1 writesdata
onRAID1arrayswith3or
more disks.
315
Higher
reliability than
RAID 5; much
higher
reliability than
a single drive
(no RAID).
Transfer
rates more
similar to
RAID1than
RAID 0.
Reads are
up to two
times faster
thanasingle
drive.
Writes are
about the
same as a
single drive.