RAID Levels

The Thecus N4100+ supports standard RAID levels 0, 1, 5, and JBOD. You choose
a RAID level when you create a system volume. The factors for selecting a RAID
level are:

• Your requirements for performance
• Your need for data security
• Number of hard disk drives in the system, capacity of hard disk drives in
• Will you be required to perform a RAID data recovery

the system

The following is a description of each RAID level:

RAID 0
RAID 0 is best suited for applications that need high bandwidth but do not require
a high level of data security. The RAID 0 level provides the best performance of
all the RAID levels, but it does not provide data redundancy.
RAID 0 uses disk striping and breaking up data into blocks to write across all hard
drives in the volume. The system can then use multiple hard drives for faster
read and write. The stripe size parameter that was set when the RAID was
created determines the size of each block. No parity calculations complicate the
write operation.

RAID 1

RAID 1 mirrors all data from one hard disk drive to a second one hard disk drive,
thus providing complete data redundancy. However, the cost of data storage
capacity is doubled.This is excellent for complete data security.

RAID 5

RAID 5 offers data security and good performance. It is best suited for networks
that perform many small I/O transactions at the same time, as well as
applications that require data security such as office automation and online
customer service. Use it also for applications with high read requests but low
write requests.

RAID 5 includes disk striping at the byte level and parity information is written to
several hard disk drives. If a hard disk fails the system uses parity stored on each
of the other hard disks to recreate all missing information.

JBOD

Although a concatenation of disks (also called JBOD, or “Just a Bunch of Disks”) is
not one of the numbered RAID levels, it is a popular method for combining
multiple physical disk drives into a single virtual one. As the name implies, disks
are merely concatenated together, end to beginning, so they appear to be a
single large disk.As the data on JBOD is not protected, one drive failure could result total data loss.

Stripe Size

The length of the data segments being written across multiple hard disks. Data is
written in stripes across the multiple hard disks of a RAID. Since multiple disks
are accessed at the same time, disk striping enhances performance. The stripes
can vary in size.