Thecus Technology M3800 - Manual (Page 97)

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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.
Disk Usage
When all 3 disks are of the same size, and used in RAID, M3800 disk usage
percentage is listed below:
RAID Level Percentage Used
RAID 0 100%
RAID 1 50%
RAID 5 66%
JBOD 100%