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APPENDIX
The SATA RAID controller redistributes the original volume set
over the original and newly added disks, using the same fault-
tolerance conguration. The unused capacity on the expand raid
set can then be used to create an additional volume sets, with a
different fault tolerance setting if user need to change.
• Online RAID Level and Stripe Size Migration
For those who wish to later upgrade to any RAID capabilities, a
system with Areca online RAID level/stripe size migration allows
a simplied upgrade to any supported RAID level without having
to reinstall the operating system.
The SATA RAID controllers can migrate both the RAID level and
stripe size of an existing volume set, while the server is online
and the volume set is in use. Online RAID level/stripe size mi-
gration can prove helpful during performance tuning activities
as well as when additional physical disks are added to the SATA
RAID controller. It is only possible to migrate to a higher RAID
level by adding a disk; disks in an existing array can’t be recon-
gured for a higher RAID level without adding a disk.
Online migration is only permitted to begin, It all volumes to be
migrated are in the normal mode. During the migration process,
the volume sets being migrated are accessed by the host sys-
tem. In addition, the volume sets with RAID level 1 is 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 migration is completed,
the volume set transitions to degraded mode.
• Online Volume Expansion
Performing a volume expansion on the controller is the process
of growing only the size of the latest volume. A more exible
option is for the array to concatenate an additional drive into the
RAID set and then expand the volumes on the y. This happens
transparently while the volumes are online, but, at the end of
the process, the operating system will detect free space at after
the existing volume.
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