Raid 5: striping, parity distributed among drives, Jbod (just a bunch of disks) – Sonnet Technologies Fusion QR (With Drives) User Manual

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6 – Drive Mode Descriptions

RAID 5: Striping, Parity Distributed Among Drives

RAID 5 configuration increases reliability while using fewer
drives than RAID 10 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 18. When the failed drive is replaced,

the parity data on the three other drives is used to rebuild
the RAID volume with data spread across all four drives.

In the QR, RAID 5 configuration offers 75% of the four
drives’ total capacity. For example, if your system has four
4TB drives, the total unformatted capacity is 16TB. After
configuring the drives in RAID 5 mode, approximately 12TB
is available for storage, with the other 4TB set aside for parity.

JBOD: Just a Bunch of Disks

JBOD mode enables all four drives to be available
individually at the same time for normal storage operations.
See

Figure 19. Note that when you connect the QR to your

computer via eSATA connection, the eSATA controller to which
the storage system is connected must offer port multiplier
support
; refer to the eSATA controller’s documentation or
the manufacturer’s Website for information. If the eSATA
controller does not offer 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.

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 18

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 19

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