|The Hotswap-Project´s goal is to develop a technique for replacing
generic hardware components of open, industrial computers during runtime.
The replacement of hardware components may be necessary due to the following
Using conventional industrial computers, a system shutdown is inevitable
in these cases, which leads to system unavailability during repair / upgrade.
This downtime can be avoided by employing the hotswap technology. Furthermore,
structural redundancy at peripheral bus level is possible, e.g. using two
redundant ethernet-cards in the same system. Additionally one could
use multiple system boards at the same bus, which would lead to a architectur
similar to so-called server-clusters. These aggregations of redundant off-the-shelf
computers enable a high-availability solution at relatively low costs.
The only difference between nowadays server-clusters and a hot-swap based
redundant systems would be the interconnection network: a LAN on the one
hand, and direct connection via the local bus on the other hand. Using
HotSwap-technology would lead to the following advantages over conventional
Exchange of a failed component with an identical component.
Upgrade of a component. (that means: remove a component and replace it
with a different one.)
Adding a new component.
Introducing the HotSwap-ability affects the system on all levels of its
architecture, reaching from disturbing electrical effects on the interconnecting
bus´ signals during insertion and removal of boards to influences
on the systems highest level, the application layer. The goals of our project
are to evaluate these impacts, propose possible solutions in a generic
way and finally to implement a prototype of a complete HotSwap system based
on the CompactPCI local bus.
Only "live-critical" components have to be redundant, which will decrease
The fail-over time will be shorter, because no data transfer over the relatively
slow LAN will be necessary. The fail-over time has a major impact on the
systems mean downtime.
Exchange of a failed component will be very easy. This will lead to shorter
repair times and lower maintenance costs.
At the moment, our efforts are concentrated on three main topics: