CRU DataPAK - Manual (Page 6)

DataPAK - Manual
Page 6
3. Understanding RAID
3.1 Consider your RAID type (Skip ahead if you purchased a pre-configured unit.)
A RAID (Redundant Array of Independent Disks) is an array of multiple hard drives that are
combined in a way that provides faster performance and/or data safety. Your DataPAK
unit is capable of creating and managing several different varieties of RAID. You may
choose your preferred RAID level based on factors such as disk capacity, desired data
safety, and desired performance.
3.1.1 Summary of RAID Levels
The DataPAK RAID supports RAID levels 0, 1, 3, 5 and 10. The RAID 10 is the most com-
monly used application for the DataPAK RAID. In RAID 10 the DataPAKs are mirrored,
allowing a DataPAK to be removed while allowing the data to be accessible.
RAID Features and Performance
RAID
Level Description Min.
Drives
Max.
Drives
Data Reliability Data Transfer Rate
0 Also known as striping. Data distributed across
multiple drives in the array. There is no data
protection. 1 4 No data Protec-
tion Very high
1 Also known as mirroring. All data replicated
on separated disks. RAID 1 is almost always
2 disks.
This is a high availability solution, but due
to the 100% duplication, it is also a costly
solution. 2 2 Very Reliable;
Higher than
RAID 3, 5 Reads are higher
than a single disk;
Writes are similar
to a single disk
3 Also known as Bit-Interleaved Parity. Data and
parity information is subdivided and distributed
across all disks. Parity must be equal to the
smallest disk capacity in the array. Parity
information is normally stored on a dedicated
parity disk. 3 4 Lower than
RAID 1, 10;
Higher than a
single drive Reads are similar
to RAID 0; Writes
are slower than a
single disk
5 Also known as Block-Interleaved Distributed
Parity. Data and parity information is subdivided
and distributed across all disks. Can withstand
the failure of one drive, and 75% of drive
capacity is usable. 3 4 Lower than
RAID 1, 10;
Higher than a
single drive Reads are similar
to RAID 0; Writes
are slower than a
single disk
10 Also known Block-Interleaved Parity. Data and
parity information is subdivided and distributed
across all disk. Parity must be the equal to
the smallest disk capacity in the array. Parity
information normally stored on a dedicated
parity disk. 4 4 Very Reliable;
Higher than
RAID 3, 5 Transfer rates are
more like RAID 1
than RAID 0