User manual

written to different disks. There are at least 3 members to a Parity RAID set. The following example illustrates how the parity is

rotated from disk to disk.

Parity RAID uses less capacity for protection and is the preferred method to reduce the cost per megabyte for larger

installations. Mirroring requires 100% increase in capacity to protect the data whereas the above example only requires a 50%

increase. The required capacity decreases as the number of disks in the group increases.

2.3.5 Concatenation

Concatenation combines multiple disks or segments of disks into a single large volume. It does not provide any data

protection or performance improvement but can be useful for utilizing left over space on disks. Concatenation allows the

segments which make up the volume to be of difference sizes.

2.3.6 JBOD (Just Bunch of Disks)

The JBOD is a virtual disk that can either be an entire disk drive or a segment of a single disk drive. For home edition, JBOD

function only supports one disk.

2.4 RAID Volume Status

A RAID Volume can be in any one of the following statuses.

Status Meaning

Good All disks are currently functioning Normal

Degraded For RAID levels which contain some data protection, one or more disks have failed but the data is still

available via the RAID algorithms. The failed disk should be replaced as soon as possible.

Rebuilding A failed disk drive has been replaced and the data is being regenerated on the replacement disk. When

complete, the RAID Group will return to Good status.

Resynchronizing An error has occurred which requires that the RAID algorithms be regenerated on this RAID Group.

When complete, the RAID Group will return to Good status.

Failed One or more disks have failed and RAID algorithms can no longer regenerate the data. The minimum

number of failures required to reach this state depends on the RAID level

RAID 0, Contiguous, Concatenated, JBOD: Single disk failure

RAID 1, 5, 10: Two drive failure