Areca ARC-1110 User Manual

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mation or data on that RAID set. Therefore, if a server fails, the 

RAID set disk drives can be moved to another server with an 
Areca RAID controller and the disks can be inserted in any order.

Online Capacity Expansion makes it possible to add one or more 

physical drives to a volume set without interrupting server op-

eration, eliminating the need to backup and restore after recon-

figuration of the RAID set. When disks are added to a RAID set, 

unused capacity is added to the end of the RAID set. Then, data 

on the existing volume sets (residing on the newly expanded 

RAID set) is redistributed evenly across all the disks. A contigu-

ous block of unused capacity is made available on the RAID set. 

The unused capacity can be used to create additional volume 

sets.

A disk, to be added to a RAID set, must be in normal mode (not 

failed), free (not spare, in a RAID set, or passed through to 

host) and must have at least the same capacity as the smallest 

disk capacity already in the RAID set.

Capacity expansion is only permitted to proceed if all volumes 

on the RAID set are in the normal status. During the expansion 

process, the volume sets being expanded can be accessed by 

the host system. In addition, the volume sets with RAID level 1, 

1E, 3, 5 or 6 are protected against data loss in the event of disk 

failure(s). In the case of disk failure, the volume set transitions 

from “migrating” state to “migrating+degraded“ state. When the 

expansion is completed, the volume set would then transition to 

“degraded” mode. If a global hot spare is present, then it further 

transitions to the “rebuilding” state.