User`s manual

2.1.4 R0 MODE
The R0 MODE storage policy distributes access across all hard disks. R0 MODE presents the best data speed
but no data redundancy. R0 MODE storage policy accelerates hard disk drive operating speed by using many
disks in parallel. Hard disk drive data segments are written to different disks simultaneously which increases
performance while sacrificing data redundancy.
To implement the R0 MODE storage policy, the AES-S3504UE Storage creates a single virtual
volume that is striped across both hard drives, with a storage capacity that is five times of the smallest drive.
2.1.5 R1 MODE
The R1 MODE storage policy stores all data in duplicate on separate drives to protect against data loss due to
drive failure. One drive mirrors the other at all times. Every write operation goes to both drives. R1 MODE
provides the highest level of data protection for critical data that you cannot afford to lose if a hard drive fails, but
halves the amount of storage capacity because all data must be stored twice. The resulting storage capacity of
the virtual R1 volume will be equivalent to the size of one hard drive (if both drives are the same) or the smaller of
the two drives (if they are different).
If one drive fails, the R1 volume is still usable, but it is in a vulnerable state because its mirrored hard drive is
inaccessible. When the offline drive comes back online, the appliance begins a rebuild process immediately to
restore data redundancy. A message appears in the LED indicator to notify you that a rebuild is in progress.
Although the volume remains available during the rebuild process, the volume is susceptible to data loss through
damage to the remaining drive until redundancy is restored at the end of the rebuild and verification process. Host
AES-S3504UE User’s Manual Ver. 091015
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