Backup is
the process of sending or moving data to a secondary storage media
or secondary management system for the purpose of preserving the data.
Devices with backup capability typically have a built-in watchdog
application that continuously monitors the link state of each network,
and a token switching mechanism. When the watchdog detects that the
primary link is down, it automatically switches to the secondary link
to ensure continuous uptime.
Industrial automation environments usually have a number of devices
with data that needs to be collected. Typically, these devices collect
data from the factory floor and send the data to a data server on the
same local area network. There is no guarantee, however, that the
connection link between these devices and the local data server will
always be active. A cable that connects the device and the data server
could be disconnected accidentally, or the data server could crash
for any reason. For businesses with critical data that must be backed
up continuously at all costs, a higher degree of fault tolerance in
data transmission is required. Remote backup, a capability that more
advanced device servers provide, could be implemented to address this
issue.
A device server that provides remote backup capability can be configured
to check the device connection to the local data server periodically,
typically at 3 to 5-second intervals. When it detects that the link is down (for example, if there is a cable problem or the backup
server is down), it will automatically switch to remote backup mode
and send data to a remote alternate server via GSM/GPRS or PSTN. This
ensures that critical data collected from factory devices is not lost
because the local data server is inaccessible or unavailable.
