Sonnet Technologies Fusion R400S RAID (Without Drives) - Manual (Page 6)

4
Drive Mode Descriptions
RAID 5: Striping, Parity Distributed Among Drives
RAID 5 increases reliability while using fewer drives than
mirroring by using parity redundancy: parity is distributed
across multiple drives. Any one of the four drives can fail,
and the volume will continue to function. See
Figure 8.
RAID 5 formatting offers 75% of the four drives’ total
capacity. For instance, if your system has four 2TB drives, the
total unformatted capacity is 8TB. After RAID 5 formatting,
approximately 6TB is available for storage, with the other
2TB used for parity.
JBOD (PM): Just a Bunch of Disks
JBOD configuration enables all four individual drives to be
available for normal storage operations with no special data
protection by combining several drives into one large drive.
See
Figure 9. Note that for JBOD operation, the R400S RAID
requires the use of an eSATA controller that offers port multiplier
support; refer to the eSATA controller’s documentation or
the manufacturer’s Website for information. If you format
the drives as JBOD and use the R400S RAID with an eSATA
controller with no port multiplier support, only one of
the four drives will be accessible. JBOD provides no data
protection.
JBOD offers the full capacity of each of the drives.
Clone: Data Mirrored on All Four Drives
Clone mode enables all four drives to store the same files.
You may remove one of the four drives and replace it with
another drive; the data will be copied without further action
from you. Depending on the capacity of the drives you’ve
installed, this process may take hours to complete.
Disk 1
Data 1
Data 5
Data 9
Parity
10–12
Disk 2
Data 2
Data 6
Parity 7–9
Data 10
Disk 3
Data 3
Parity 4–6
Data 7
Data 11
Disk 4
Parity 1–3
Data 4
Data 8
Data 12
RAID 5:
Striping, Parity Distributed Among Drives
Stripe 1
Stripe 2
Stripe 3
Stripe 4
Figure 8
Disk 1
Data 1
Data 2
Data 3
Data 4
Disk 2
Data 5
Data 6
Data 7
Data 8
Disk 3
Data 9
Data 10
Data 11
Data 12
Disk 4
Data 13
Data 14
Data 15
Data 16
JBOD (Just a Bunch of Disks)
Figure 9
Disk 1
Data 1
Data 2
Data 3
Data 4
Disk 2
Data 1
Data 2
Data 3
Data 4
Disk 3
Data 1
Data 2
Data 3
Data 4
Disk 4
Data 1
Data 2
Data 3
Data 4
Clone (Data Mirrored on All Drives)
Figure 10