System information

1 Introduction
1.1 Outline
The following sections give an overview about the target system of this thesis. They also
discuss existing remote access tools for computer systems. The heart of the hardware based
remote control presented in this thesis is the CHARM
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PCI card which will be referenced
simply as CHARM in the rest of the text. The features of the card are summarized in
section 1.5.1. The architecture of the card is illustrated in chapter 2. The CHARM has its
own operating system which controls the hardware units of its board. Chapter 3 discusses
the operating system of the card. A central feature of the CHARM is the graphic card
function. The CHARM replaces the primary graphic card of the computer. The reason
of this approach and the implementation of the VGA function is explained in chapter 4.
Chapter 5 illustrates the device emulation of the CHARM. It is used for the interaction
with the host computer. Besides the remote access feature of the CHARM, the card also
monitors the host computer. The monitoring capability of the card is illustrated in chapter
6. The CHARM can also be used for other applications than the remote control of a com-
puter. Chapter 8 explains the other functions which were implemented with the CHARM.
Experimental results and experiences with the CHARM are discussed in chapter 9. Chapter
10 summarizes the application of the CHARM and gives an outlook over the CHARM.
1.2 ALICE Experiment
ALICE is one of the four experiments at the Large Hadron Collider (LHC) [11, 12]. The LHC
is an accelerator ring which was built for the European Organization for Nuclear Research
(CERN). Figure 1.1 shows the LHC ring and the location of the main experiments: CMS,
ATLAS
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, ALICE, LHCb
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. The aim of ALICE is to study the physics of strongly interacting
matter at extreme energy densities, where the formation of a new phase of matter, the quark-
gluon plasma, is expected. In the ALICE experiment lead ions collide at a total center of
mass energy of 1148.0 TeV [12]. The ALICE setup includes a variety of detectors focusing
on different particle properties. The biggest data source of ALICE is the time projection
chamber (TPC) which is being readout at a rate of up to 200 Hz [12]. Every such event
is about 82 MB in size. The most interesting events are selected by the so-called trigger
system. This approach optimizes the usage of the data bandwidth of the detector.
The ALICE trigger system is separated into four levels: Level-0, Level-1, Level-2 and the
High-Level Trigger(HLT) [12, 15]. They differ by the amount of data on which the decision
is based and by the complexity of the data analysis.
1.3 HLT Computer Cluster
The HLT is designed to analyze LHC events produced in the ALICE detector in an online
matter [16, 17]. The heart of the HLT consists of a computing cluster of several hundreds
of dual-processor nodes [18]. The nodes will be connected via Gigabit Ethernet [19]. Figure
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Computer Health and Remote Management
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A Toroidal LHC Apparatus [13].
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Large Hadron Collider beauty [14].
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