ATTO Technology FastStream VT 5300 Installation And Operation Manual page 38

Appendix C
The ATTO FastStream VT provides instant hardware data protection and intelligence to existing SCSI
storage independent of the storage type.
CAUTION CAUTION
Selecting RAID configuration causes all
previous storage data on the drive to be
erased. Make sure all of your information is
backed up before setting up RAID groups.
The ATTO FastStream VT allows RAID
functionality. In general, the process begins with
individual drives also called block devices.
Note
If a drive has corrupt or outdated configuration
data, that drive cannot be assigned to any
RAID group. Ensure all drives to be assigned
to RAID groups are configured properly. Refer
to Initialize and verify drives
A RAID group is a virtual, independent single
drive whose data is written to physical drives
according to a RAID algorithm. The ATTO
FastStream VT supports JBOD, RAID Level 0,
RAID Level 1, RAID Level 10 and RAID Level
5.
RAID improves data accessibility and reliability
during normal operations, however, you still need
a good backup strategy for long-term protection
of your data.
JBOD (Just a Bunch of Disks)
JBOD (Just a Bunch of Disks) configuration
allows many individual drives to be available for
normal storage operations with no special data
protection.
Using the ATTO FastStream VT allows you to
concatenate several individual drives into one
large drive.
A JBOD drive can be constructed as a special case
of a RAID group. When multiple physical drives
are assigned to a JBOD RAID group, their storage
v
ATTO Technology Inc. FastStream VT 5300 Installation and Operation Manual
Designing RAID groups
areas appear as a single spanned area of storage.
The ATTO FastStream VT supports 1 to 32 drives
per JBOD-configured RAID group.
Exhibit A-2 JBOD: Just a Bunch of Disks: no
redundancy; each disk is treated independently
Disk 0 Disk 1 Disk 2
D0
D1
D2
D3
RAID Level 0
on page 7.
RAID Level 0 (striping) is based on the fact that
increased performance can be achieved by
simultaneously accessing data across multiple
drives, increasing data transfer rates while
reducing average access time by overlapping
drive seeks. RAID Level 0 groups provide data
that is striped across several drives. Drives are
accessed alternately, as if stacked one on top of
the other.
RAID Level 0 provides no data protection. If one
drive fails, all data within that stripe set is lost.
The ATTO FastStream VT supports 2 to 32 drives
per RAID Level 0 group.
RAID Level 0 is used by applications requiring
high performance for non-critical data.
Exhibit A-3 Exhibit 1.0-2 RAID Level 0, no
redundancy
Stripe Disk 0 Disk 1 Disk 2 Disk 3 Disk 4 Disk 5
0
1
2
3
JBOD
D4 D8
D5 D9
D6 D10
D7 D11
RAID Level 0
D0 D1 D2
D6 D7 D8
D12 D13 D14 D15
D18 D19 D20 D21
D3 D4 D5
D9 D10 D11
D16 D17
D22 D23