Spectra Logic Spectra 12000 - Manual (Page 67)

Chapter 7. Configuring the Spectra 12000 E-QIP 67
Sharing Tape Devices
TAOS ITP and TAOS NDMP both allow a set of tape resources to be
shared between multiple hosts. Care must be taken to ensure that
multiple requests are not being sent to same tape drive at the same time.
With TAOS NDMP, there is typically a backup application server that
manages access to the tape drives. Even though multiple NAS devices
can access the tape device directly these requests are routed through a
single backup server. This server, then, is responsible for managing
access to the drives. As long as the devices and NAS clients are
configured properly in the software, resource contention is eliminated.
Access to TAOS NDMP functionality is also password protected--any NAS
host wishing to write to the Spectra 12000 library must authenticate
themselves with the correct username and password. This is also
generally set up in the backup software.
With TAOS ITP, there may be many backup applications on many hosts,
all responsible for managing their own access to the tape drives, and as
the E-QIP looks like a locally attached resource to each configured host,
each host has no idea that other hosts also have access. There are three
ways to manage resource contention with TAOS ITP. First, the E-QIP will
only be visible to hosts where the TAOS ITP driver has been installed.
Second, the TAOS ITP configuration utilities in the E-QIP allow you to
configure IP address ranges of hosts that can access the library. Finally,
devices can be locked during use by going through one of the available
configuration interfaces. When a device has been locked, no other host
can gain access to the drive until it is unlocked.
In any case, if multiple hosts will be accessing the library, some access
management scheme must be implemented to prevent stored data
written by one host from being overwritten by another.
TAOS User Interfaces
There are two user interfaces available to access and change TAOS
options: a serial port interface and a TAOS ITP control panel (available
on Windows systems only). The serial interface is the only way to set the
Ethernet configuration of the library, however, once the Ethernet
parameters have been set and the unit is connected to your network, the
TAOS ITP control panel can be used to view settings.