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1.3 RAID Concepts
The basic idea of RAID (Redundant Array of Independent Disks) is to combine multiple inexpensive disk drives into
an array of disk drives to obtain performance, capacity and reliability that exceeds that of a single large drive. The
array of drives appears to the host computer as a single logical drive. The RAID subsystem provides data striping,
mirroring, XOR calculation and data verification. It supports RAID levels 0, 1, 3, 5, 10, LARGE and CLONE. All RAID
levels
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capacity can exceed 2 Terabytes. The RAID subsystem behaves as a full 48-bit addressing RAID drive and is
100% ATA compliance. From (PC) host controller, each logical device (RAID volume) controlled by the RAID system
acts just the same as single regular hard disk although a RAID system generally consists of more than one hard disk
drives. Therefore, no extra BIOS, driver or software is needed.
1.3.1 Definition of RAID Levels
Striping (RAID 0) for High Performance
Striping or RAID 0 is the segmentation of logically sequential data, such as a single
file, so that segment can be assigned to multiple hard disks in a round-robin fashion
and thus written concurrently. Advantage of RAID 0 is to achieve high performance
by accumulating each individual hard disk performance.
However, if any one hard
disk gets defective, information stored in this RAID 0 will become invalid.
The RAID subsystem will just make use of the same disk space for each hard disk
under RAID 0 condition. For example, if a RAID 0 consists of 5 different size hard
disks, the total usable space of this RAID 0 will be [capacity of smallest size hard
disk] * [the number of hard disks in this RAID 0].
Mirror (RAID 1) for High Security
Mirror or RAID1 is the replication of data onto separate hard disk in real time to
ensure continuous availability. In a RAID 1 system with two hard disks, the data in
one hard disk will be exactly the same as the data in the other hard disk. The RAID
subsystem will also make use of same size disk space in each hard disk in RAID 1.
That is, the RAID controller will write data to the same disk space in each hard disk.
When reading data, the RAID controller will read data from a specified hard disk.
Failure in a hard disk will cause the RAID controller to enter into degraded mode.
The host controller can still read/write data to the RAID without knowing any hard
disk defect. Users have to replace the hard disk then the RAID controller will enter
in on-line rebuild mode automatically. Besides, if there is only partial defect in a
hard disk, the RAID controller will read data from the other healthy hard drive.
Summary of Contents for EB400CR
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Page 22: ...21 After running the Application Program the RAID management GUI will be displayed...
Page 25: ...24 About button Displays software version...
Page 26: ...25 Alarm Buzzer Mute Click to mute the alarm buzzer...
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