108 research outputs found
ClusterRAID: Architecture and Prototype of a Distributed Fault-Tolerant Mass Storage System for Clusters
During the past few years clusters built from commodity off-the-shelf (COTS) components have emerged as the predominant supercomputer architecture. Typically comprising a collection of standard PCs or workstations and an interconnection network, they have replaced the traditionally used integrated systems due to their better price/performance ratio. As paradigms shift from mere computing intensive to I/O intensive applications, mass storage solutions for cluster installations become a more and more crucial aspect of these systems. The inherent unreliability of the underlying components is one of the reasons why no system has been established as a standard storage solution for clusters yet. This thesis sets out the architecture and prototype implementation of a novel distributed mass storage system for commodity off-the-shelf clusters and addresses the issue of the unreliable constituent components. The key concept of the presented system is the conversion of the local hard disk drive of a cluster node into a reliable device while preserving the block device interface. By the deployment of sophisticated erasure-correcting codes, the system allows the adjustment of the number of tolerable failures and thus the overall reliability. In addition, the applied data layout considers the access behaviour of a broad range of applications and minimizes the number of required network transactions. Extensive measurements and functionality tests of the prototype, both stand-alone and in conjunction with local or distributed file systems, show the validity of the concept
Supramolecular electrode assemblies for bioelectrochemistry
For more than three decades, the field of bioelectrochemistry has provided novel insights into the catalytic mechanisms of enzymes, the principles that govern biological electron transfer, and has elucidated the basic principles for bioelectrocatalytic systems. Progress in biochemistry, bionanotechnology, and our ever increasing ability to control the chemistry and structure of electrode surfaces has enabled the study of ever more complex systems with bioelectrochemistry. This feature article highlights developments over the last decade, where supramolecular approaches have been employed to develop electrode assemblies that increase enzyme loading on the electrode or create more biocompatible environments for membrane enzymes. Two approaches are particularly highlighted: the use of layer-by-layer assembly, and the modification of electrodes with planar lipid membranes
Benchmarks and implementation of the ALICE high level trigger
The ALICE high level trigger combines and processes the full information from all major detectors in a large computer cluster. Data rate reduction is achieved by reducing the event rate by selecting interesting events (software trigger) and by reducing the event size by selecting sub-events and by advanced data compression. Reconstruction chains for the barrel detectors and the forward muon spectrometer have been benchmarked. The HLT receives a replica of the raw data via the standard ALICE DDL link into a custom PCI receiver card (HLT-RORC). These boards also provide a FPGA co-processor for data-intensive tasks of pattern recognition. Some of the pattern recognition algorithms (cluster finder, Hough transformation) have been re-designed in VHDL to be executed in the Virtex-4 FPGA on the HLT-RORC. HLT prototypes were operated during the beam tests of the TPC and TRD detectors. The input and output interfaces to DAQ and the data flow inside of HLT were successfully tested. A full-scale prototype of the dimuon-HLT achieved the expected data flow performance. This system was finally embedded in a GRID-like system of several distributed clusters demonstrating the scalability and fault-tolerance of the HL
AFS Monitoring: The CERN AFS Console
CERN's AFS installation serves between 1 and 2 billion accesses per day to its around 20'000 users. Keeping track of the system's overall status and trying to find problems before the users do is not a trivial task, esp. as the installation is growing in almost all aspects. This talk will present CERN's AFS Console, a Lemon- and web-based monitoring tool used by the AFS administrators at CERN to quickly identify problematic entities (servers, partitions, volumes etc.) and to assist them in solving the issues found
Synthese, Vergleich und Anwendung von Oxazolin Liganden für die Homogene Katalyse
For the first time, a collection of different oxazoline ligands with the core
structures 2,2´-bioxazoline (box), 2-(pyridine-2-yl)-oxazoline (pyrox),
2-(2-methylpyridine-2-yl)-oxazoline (mepyrox) and 2-(quinolin-2-yl)-oxazoline
(quinox) was prepared and studied regarding their sterical and electronical
properties as well as the catalytic activity of their Ir(I) complexes. For the
investigation of electronical and sterical properties with IR spectroscopy,
Ir(I) carbonyl complexes of the oxazoline ligands were prepared. The
application of the same Ir(I) metal center guaranteed a high comparability of
the carbonyl complexes and the pre catalysts for C H activation and
hydrogentation. Furthermore, the oxazolines were applied as ligands in
heteroleptic Ru(II) complexes for surface immobilisation. For the synthesis of
box structures, a three step procedure and for pyrox, mepyrox and quinox a two
step procedure was developed. Both procedures were optimized to obtain high
conversions and to allow easy workup of the single steps. In the first step,
commercially available chiral aminols were coupled with carboxylic acids.
Since a large variety of substituted starting materials is commercially
available, a comprehensive variation of the target structures is possible.
Good to excellent total yields were achieved for 20 structurally related
compounds which were prepared in half gram scale. For the evaluation of the
electronic properties of the oxazoline ligands, square planar Ir(I) dicarbonyl
complexes were prepared and their corresponding νCO absorption frequencies
were measured by IR spectroscopy. To prepare the complexes,
[Ir(cis,cis-1,5-cyclooctadiene)Cl]2 was initially treated with different
silver salts (AgPF6, AgBF4,
Ag[tetrakis(3,5-bis(trifluoromethyl)phenyl)borate)], to exchange the chloride
for a non coordinating counterion. Subsequently, the ligand was added to give
complexes of the general composition [Ir(ligand)(cod)]X. These complexes were
converted into dicarbonyl complexes by addition of stoichiometric amounts of
CO gas at atmospheric pressure. The CO complexes were studied by ATR IR
measurements of the solid compound or as solution in tetrahydrofurane. The
interpretation of the IR measurements was supported by DFT calculations. The
carbonyl stretching frequencies of the square planar dicarbonyl
complexes[Ir(ligand)(CO)2]PF6 turned out to be mainly influenced by the steric
properties of the oxazoline ligands, while trigonal bipyramidal monocarbonyl
complexes [Ir(ligand)(cis,cis-1,5-cyclooctadiene)(CO)]PF6 reflected more the
electronical properties of the ligands. The formation of heteroleptic Ru(II)
complexes of the general composition [Ru(oxazoline)(bipyridine)X2] was
investigated. The complexes were designed to contain an oxazoline ligand
carrying the chiral information and a substituted bipyridine ligand, suitable
for further functionalisation and immobilisation on an electrode surface. The
complex synthesis started with [Ru(p-cymene)Cl2]2 or [Ru(S(CH3)2O)4(Cl)2] and
the oxazoline ligand was introduced as first or second ligand. If the
oxazoline was introduced as first ligand, the addition of a bipyridine led to
bisheteroleptic bipyridine complexes. If the oxazoline was introduced as
second ligand, an inseperable mixture, probably isomers, was obtained. The
prepared oxazolines were tested as ligands in direct aromatic and aliphatic
borylation. As catalytic system [Ir(cis,cis-1,5-cyclooctadiene)(OCH3)]2 was
used in combination with the respective ligand and bis(picanolato)diboron
served as boron source. Aromatic borylations were carried out in the neat
monosubstituted arenes such as toluene, tert-butylbenzene, anisole,
cyclohexylbenzene, trifluorotoluene and ethyl benzoate. The meta:para ratios
of the products were investigated by 1H NMR spectroscopy, showing a purely
substrate induced effect on the regioselectivity. Aliphatic borylations of
n-octane and n-hexane were unsuccessful under the applied conditions.
Hydridosilylether directed γ C H activation was carried out with a catalytic
system of [Ir(cis,cis-1,5-cyclooctadiene)(OCH3)]2 and an oxazoline ligand
instead of the usually applied 3,4,7,8 tetramethylphenanthroline ligand.
Initially ketones or alcohols were transformed into their (hydrido)silyl ether
derivatives, followed by a γ C H activation which led to the formation of an
oxasilolane. Norbornene was added stochiometrically as hydrogen acceptor. The
(hydrido)silyl ether formation was optimized and the stereochemical influence
of the chiral ligands in the C H activation step was investigated. A racemic
mixture of ((3,7 dimethyloctan 3 yl)oxy)diethylsilane served for this purpose
as substrate regarding its kinetic resolution. The products were obtained in
enantiomeric excess up to 44% ee. Precatalysts for homogeneous hydrogenation
had the general composition [Ir(ligand)(cod)]
[tetrakis(3,5-bis(trifluoromethyl)phenyl)borate)] and were prepared by initial
mixing of [Ir(cis,cis-1,5-cyclooctadiene)(Cl)]2 with
Ag[tetrakis(3,5-bis(trifluoromethyl)phenyl)borate)] and subsequent addition of
the oxazoline ligand. The hydrogenations were carried out in neat substrate or
in dichloromethane at 40 bar hydrogen pressure. The products were analyzed by
1H NMR spectroscopy and/or GC FID measurements. The oxazoline containing
complexes led to yields up to 99% and showed a high chemoselectivity for C C
double bonds when they were applied for the hydrogenation of α,β unsaturated
ketones, but no stereoselectivity was observed.Erstmalig wurde eine Sammlung verschiedener Oxazolinliganden mit den
Strukturtypen 2,2´-Bioxazolin (box), 2-(Pyridine-2-yl)-oxazolin (pyrox),
2-(2-Methylpyridine-2-yl)-oxazolin (mepyrox) und 2-(‚Chinolin-2-yl)-oxazolin
(quinox), angelegt und deren sterische sowie elektronische Eigenschaften,
sowie die katalytische Aktivität ihrer Ir(I) Komplexe, untersucht. Zur Analyse
der elektronischen und sterischen Eigenschaften mit Hilfe der IR Spektroskopie
wurden Ir(I) Carbonylkomplexe der Oxazoline synthetisiert. Die konsistente
Verwendung des Ir(I) Metallzentrums gewährleistet eine gute Vergleichbarkeit
zwischen den Carbonylkomplexen und den Präkatalysatoren für C H Aktivierung
und Hydrierung. Des Weiteren wurden die dargestellten Oxazolinstrukturen als
Liganden in heteroleptischen Ru(II) Komplexen zur zukünftigen
Oberflächenimmobilisierung verwendet. Für die Darstellung der box Strukturen
wurde eine zwei stufige und für die pyrox, mepyrox und quinox Strukturen eine
drei stufige Syntheseroute entwickelt. In beiden Syntheserouten wurde der
Schwerpunkt auf möglichst vollständige Umsätze gelegt, um zeitintensive
Aufreinigungsschritte zu vermeiden. Als Reaktionspartner für die chiralen
Aminole wurden kommerziell erhältliche Carbonsäuren gewählt. Durch die
Vielfalt der kommerziell erhältlichen Ausgangsstoffe besteht die Möglichtkeit
zur umfangreichen Variation der Zielstrukturen. Mit den entwickelten
Syntheserouten wurden gute bis hervorragende Gesamtausbeuten erreicht und
insgesamt 20 strukturell verwandte Verbindungen im halb Gramm Maßstab
dargestellt. Für die Evaluierung der elektronischen Eigenschaften der
Oxazolinliganden wurden quadratisch planare Ir(I) Dicarbonylkomplexe
dargestellt und deren νCO Schwingungsfrequenzen mit Hilfe der
Infrarotspektroskopie (IR) gemessen. Die Komplexe wurden ausgehend von
[Ir(cis,cis-1,5-cyclooctadiene)Cl]2 durch eine neuentwickelte Syntheseroute
dargestellt. Das [Ir(cis,cis-1,5-cyclooctadiene)Cl]2 wurde zunächst mit einem
Silbersalz (AgPF6, AgBF4, Ag[tetrakis(3,5-bis(trifluoromethyl)phenyl)borat]
zur Reaktion gebracht, um das Chlorid gegen ein nicht koordinierendes Gegenion
auszutauschen. Daraufolgend wurde der Ligand zugegeben, um so Komplexe der
allgemeinen Zusammensetzung [Ir(Ligand)(cis,cis-1,5-cyclooctadiene)]X zu
erhalten. Diese Komplexe wurden durch die stöchiometrische Zugabe von CO Gas
bei Atmosphärendruck in ihre Dicarbonylkomplexe überführt. Die Analyse der
Carbonylkomplexe erfolgte per ATR IR Spektroskopie der festen Substanzen sowie
durch Messungen ihrer Lösungen in Tetrahydrofuran. Die Interpretation der IR
Daten wurde durch DFT Rechnungern unterstützt. Die Carbonyl
schwingungsabsorptionen der Dicarbonylkomplexe [Ir(ligand)(CO)2]PF6 wurden
überwiegend von den sterischen Eigenschaften der Oxazolinliganden beeinflusst,
während die der Monocarbonylkomplexe
[Ir(ligand)(cis,cis-1,5-cyclooctadiene)(CO)]PF6 hauptsächlich die
elektronischen Eigenschaften der Liganden widerspigelten. Die Synthese von
heteroleptischen Ru(II) Komplexen der allgemeinen Zusammensetzung
[Ru(Oxazolin)(Bipyridin)X2] wurde ebenfalls untersucht. Die Komplexe sollten
einen chiralen Oxazolinliganden sowie einen substituierten Bipyridin Liganden
tragen. Der Bipyridinligand sollte zur Immobilisierung auf einer
Elektrodenoberfläche geeignet sein, da in zukünftigen Projekten die
Redoxeigenschaften der Komplexe auf einer solchen Elektrodenoberfläche
studiert werden sollen. Die Komplexsynthese wurde entweder ausgehend von
[Ru(p-cymene)Cl2]2 oder [Ru(S(CH3)2O)4(Cl)2] durchgeführt, wobei der
Oxazolinligand als erster oder zweiter Ligand eingeführt wurde. Allerding
konnte ein Bipyridin Ligand den zuerst eingeführten Oxazolinliganden
vollständig aus dem Komplex verdrängen, sodass fast ausschließlich
bisheteroleptische Bipyridinkomplexe gebildet wurden. Wurde der Oxazolin
Ligand als zweiter eingeführt, bildeten sich die Produktkomplexe als
untrennbare Mischungen, vermutlich aus verschiedenen Isomeren. Die gewünschten
heteroleptischen Rutheniumkomplexes konnten nicht als isolierte Strukturen
dargestellt werden. Die dargestellten Oxazoline wurden als Liganden in
direkter aromatischer und aliphatischer Borylierung verwendet. Als
katalytisches System wurde eine Kombination aus
[Ir(cis,cis-1,5-cyclooctadiene)(OCH3)]2 und dem entsprechenden Liganden
verwendet, wobei Bis(picanolato)diboran als Borquelle fungierte und die
Reaktionen in reinem Substrat durchgeführt wurden. In der aromatischen
Borylierung fanden monosubstituierte Aromaten wie Toluol, tert-Butylbenzol,
Anisol, Cyclohexylbenzol, Trifluortoluol und Ethylbenzoat als Substrate
Verwendung. Gegenstand der Analyse war die Bestimmung des meta:para
Verhältnisses der Produkte durch 1H NMR Spektroskopie, wobei ein reiner
substratinduzierter Effekt auf die Regioselektivität festgestellt werden
konnte. Die aliphatische Borylierung von n-Oktan und n-Hexan gelang unter den
angewendeten Bedingungen nicht. Die hydridosilylether dirigierte γ C H
Aktivierung wurden mit einem katalytischen System aus
[Ir(cis,cis-1,5-cyclooctadiene)(OCH3)]2 und einem Oxazolinliganden, der den
üblicherweise verwendeten 3,4,7,8 tetramethylphenanthrolin Liganden ersetzte,
durchgeführt. Zunächst wurden Ketone oder Alkohole in ihre (Hydrido)silylether
umgesetzt, woraufhin eine γ C H Aktivierung unter Ausbildung eines Oxasilolans
stattfand. Norbornen wurde als stöchiometrisch eingesetzter
Wasserstoffakzeptor den Reaktionsmischungen zugefügt. Die Bildung der
Hydridosilylether wurde optimiert und der stereochemische Einfluss der
chiralen Liganden in der C H Aktivierung untersucht. Als Substrat diente für
diesen Zweck ((3,7 Dimethyloctan 3 yl)oxy)diethylsilan, dessen kinetische
Racemattrennung analysiert wurde. Die Produkte wurden mit enantiomeren
Überschüssen bis zu 44% ee erhalten. Präkatalysatoren für die homogene
Hydrierung waren von der generellen Zusammensetzung
[Ir(ligand)(cis,cis-1,5-cyclooctadiene)][tetrakis(3,5-bis(trifluoromethyl)phenyl)borat]
und wurden durch vorangehendes Mischen von [Ir(cis,cis-1,5-cyclooctadiene)Cl]2
mit Ag[tetrakis(3,5-bis(trifluoromethyl)phenyl)borat] und anschließender
Zugabe des entsprechenden Oxazolin Liganden dargestellt. Die Hydrierungen
wurden in reinem Substrat oder in Dichlormethan bei einem Wasserstoffdruck von
40 bar durchgeführt und die Produkte anhand von 1H-NMR Spektroskopie und/oder
GC FID analysiert. Die oxazolinhaltigen Komplexe erzielten Ausbeuten bis zu
99% und zeigten eine hohe Chemoselektivität für C C Doppelbindungen bei der
Verwendung von α,β ungesättigten Ketonen als Substrate. Eine
Stereoselektivität konnte nicht beobachtet werden
OpenStack Summit
In response to the user demand for a light-weight provisioning of distributed file system shares, the OpenStack and Ceph teams at CERN have recently added Manila/CephFS to their service catalogues. While leveraging the operational experience with a 190'000 core OpenStack deployment and a 12 PB Ceph cluster for such a self-service kiosque suggested itself, the service design and setup phases were followed by a number of functionality and stress tests to ensure the individual components are ready for production use. The final service design and the results obtained during the pre-production phase, for instance when scaling to a large number of Manila and CephFS clients or the integration with Magnum/Kubernetes, will be presented alongside the initial use cases and our first experiences running these new services in production
Successful high-risk coronary angioplasty in a patient with cardiogenic shock under circulatory assist with a 16F axial flow pump
Building an organic block storage service at CERN with Ceph
Emerging storage requirements, such as the need for block storage for both OpenStack VMs and file services like AFS and NFS, have motivated the development of a generic backend storage service for CERN IT. The goals for such a service include (a) vendor neutrality, (b) horizontal scalability with commodity hardware, (c) fault tolerance at the disk, host, and network levels, and (d) support for geo-replication. Ceph is an attractive option due to its native block device layer RBD which is built upon its scalable, reliable, and performant object storage system, RADOS. It can be considered an 'organic' storage solution because of its ability to balance and heal itself while living on an ever-changing set of heterogeneous disk servers. This work will present the outcome of a petabyte-scale test deployment of Ceph by CERN IT. We will first present the architecture and configuration of our cluster, including a summary of best practices learned from the community and discovered internally. Next the results of various functionality and performance tests will be shown: the cluster has been used as a backend block storage system for AFS and NFS servers as well as a large OpenStack cluster at CERN. Finally, we will discuss the next steps and future possibilities for Ceph at CERN
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