138
Appendix 1
What Is RAID
The acronym RAID stands for Redundant Array of Independent Drives, a method to combine a
number of small, inexpensive drives into an array which offers more functionality than a single
large disk with comparable capacity, while simultaneously taking advantage of the individual disks
to increase the efficiency of the system. In other words, during the writing process, data is split
into segments and stored on multiple disks; likewise, during the reading process, data is retrieved
simultaneously from multiple disks in order to increase the access speed of the array.
RAID can also be configured to use part of the disk capacity for mirroring or redundant data, thus
preserving the integrity of the system in case one of the disks in the array fails.
NAS-3200 supports the RAID 0 and RAID 1 volumes, and NAS-3400 supports RAID 0, RAID 1,
RAID 5, and RAID 5 with Spare, described below:
RAID level
Functionality
RAID 0
Offers Striping, a process where multiple disks are combined to form
one virtual large disk, but without safety measures.
RAID 1
Half of the disks are used for backup purposes; the content of disk A is
mirrored to disk B to assure data integrity. The available storage space
is only one half of total physical disk capacity.
RAID 5
This configuration includes a backup option. It treats multiple disks as
one virtual disk to increase access speed. It uses parity mode to store
redundant data on a space equal to the size of one disk for later data
recovery. The actual available storage space in a system with n disks
is thus n-1 hard disks.
RAID 5 with Spare
RAID 5 with Spare adds one spare disk to the RAID 5 array, allocating
one for redundancy and the second one as a spare. The actual
available storage space in a system with n disks is thus n-2 hard disks.
Each of the RAID configurations offers a different disk capacity and level of safety. When making
your choice, consider the following:
1. The bigger the available space, the fewer safeguards the system has.
2. For any RAID array, the capacity of the array is determined by the smallest hard disk. E.g., for a
RAID 1 array created with one 20 GB and one 30 GB hard disks, the total available capacity is
defined based on the 20 GB hard disk. Therefore you should always choose to use hard disks
with identical size to create a RAID array.
Summary of Contents for NAS-3200
Page 1: ...Network Attached Storage RAID Server NAS 3200 NAS 3400 User s Manual...
Page 35: ...29 4 2 Server Configuration 4 2 1 Basic Configuration General tab...
Page 86: ...80 This page shows the status of volume layout in the NAS server 4 5 3 Cache Setup...
Page 110: ...104 2 Click the Restore button to run the restoration wizard...
Page 127: ...121 6 3 4 User Preferences Upload...