Sonnet Technologies Fusion R400S RAID (With Drives) - Manual (Page 10)

8
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 12.
RAID 5 formatting offers 75% capacity 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 13. 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 12
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 13
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 14