Overland Storage REO 9000 - Manual (Page 16)

16 X Reviewing REO 9000 Concepts and Requirements
Overland Storage REO 9000 with ProtectionPAC Software
If you use a RAID 5 configuration, you can also set aside a disk drive for
each physical host (controller); that is, you can create a hot spare. These
disk drives remain in standby mode, and you can use them immediately
if another disk fails.
Tape Emulation
The ProtectionPAC software includes two tape emulation features, which
you can use to create virtual linear tape-open (LTO-2) tape devices that
provide 2-to-1 compression ratios with typical data sets (actual
performance might vary with application). When you use tape emulation,
the disk drives on the REO Appliance appear to your backup software as
LTO-2 tape drives, which simplifies the setup process while
simultaneously providing data compression and the attributes of backing
up data to disk.
Depending on the configuration that you use, you get a different number
of virtual LTO-2 devices. In the just-a-bunch-of-disks (JBOD)
configuration, you can have up to 24. If you use RAID 0 or 5 without
logical volumes, you can have four. If you use logical volumes with
RAID 0 or 5, you can create up to 64 virtual LTO-2 devices.
If you decide to use tape emulation, you also have the option of using
fixed-length (Tape) or dynamic-length (Dynamic Tape) devices. To take
advantage of the Dynamic Tape option, you must use logical volumes,
which is described in the next section. Using Dynamic Tape lets you
create devices that adjust to the size of individual backup jobs.
Logical Volume Management (LVM)
With LVM, you can combine the two physical RAID volumes into
multiple logical volumes (partitions) of different sizes and assign logical
unit numbers (LUNs) to represent the different volumes, or REO devices.
This feature lets you set up and assign devices to different systems
according to your needs and the configuration and type of storage
network that you use.
Using this feature in the ProtectionPAC software, you can create up to 64
LUNs, and you can reassign space allocation for disk or standard (not
dynamic) virtual tape devices, in 1 gigabyte (GB) increments, on the fly.
Reviewing Pre-Installation Requirements
Before attempting to operate the REO Appliance with your backup
servers, verify that your network meets the minimum requirements
specified in the following sections.
Important: If you purchased multiple units, set up (attach and
configure) one unit at a time. The target names must be unique within
a network; that is, if you are using multiple appliances, you must
change the default target names.
Also, be aware that the keys are not interchangeable and Overland
strongly recommends that you make a backup copy of the files on the
keys before and after you configure them.