CRIC and Rucio integration for CMS Data Management
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Condomitti, Fabio↗
Engineering topics
Ratnikova, N.
Publications and source records attributed to Ratnikova, N..
CRIC and Rucio integration for CMS Data Management
The Large Hadron Collider (LHC) at CERN smashes protons together at close to the speed of light with seven times the energy of the most powerful accelerators built up to now. Some of the collision energy is turned into mass, creating new particles which are observed in the Compact Muon Solenoid (CMS) particle detector. CMS data is analyzed by scientists around the world to build up a picture of what happened at the heart of the collision. This will help us answer questions such as: ”what is the Universe really made of and what forces act within it?” and ”what gives everything substance?”. All the data produced by the experiment are collected and stored in a distributed system, since it must provide an high throughput and performing access to these data to scientists and physicists spread all over the world. In order to answer the previous questions and many others, CMS users must first obtain a copy of a portion of these data, and then to analyze it, therefore the first challenge is to decide in which storage site to save this duplicate so they can access it as quickly as possible. The second issue is each storage site shares a limited memory space with many CMS users, and each one needs to be assigned to a well defined personal amount of storage to pin data he needs. The main goal of my Summer Internship is to make scalable and automatic this user-site mapping which is based on a preexisting policy, proving a structured and organized algorithm to accomplish this task. Hence we are going to define, and solve, the main challenges encountered, and the technical solution used to generalize the algorithm to handle different policies for different countries.
43 PARTICLE ACCELERATORS↗
Comprehensive Monitoring for Heterogeneous Geographically Distributed Storage
Storage capacity at CMS Tier-1 and Tier-2 sites reached over 100 Petabytes in 2014, and will be substantially increased during Run 2 data taking. The allocation of storage for the individual users analysis data, which is not accounted as a centrally managed storage space, will be increased to up to 40%. For comprehensive tracking and monitoring of the storage utilization across all participating sites, CMS developed a space monitoring system, which provides a central view of the geographically dispersed heterogeneous storage systems. The first prototype was deployed at pilot sites in summer 2014, and has been substantially reworked since then. In this paper we discuss the functionality and our experience of system deployment and operation on the full CMS scale.
Ratnikova, N.↗
Request for All - A Generalized Request Framework for PhEDEx
PhEDEx has been serving CMS community since 2004 as the data broker. Every PhEDEx operation is initiated by a request, e.g. request to move or to delete data, and so on. A request has it own life cycle, including creation, approval, notification, and book keeping and the details depend on its type. Currently, only two kinds of requests, transfer and deletion, are fully integrated in PhEDEx. They are tailored specifically to the operations' workflows. To be able to serve a new type of request it generally means a fair amount of development work. After several many years of operation, we have gathered enough experience to rethink the request handling in PhEDEx. Generalized Request Project is set to abstract such experience and design a request system which is not tied into current workflow yet it is general enough to accommodate current and future requests. The challenges are dealing with different stages in a request's life cycle, complexity of approval process and complexity of the ability and authority associated with each role in the context of the request. We start with a high level abstraction driven by a deterministic finite automata, followed by a formal description and handling of approval process, followed by a set of tools that make such system friendly to the users. Since we have a formal way to describe the life of a request and a mechanism to systematically handle it, to serve a new kind of request is merely a configuration issue, adding the description of the new request rather than development effort. In this paper, we share the design and implementation of a generalized request framework and the experience of taking an existing serving system through a re-design and re-deployment.
Huang, C.-H.↗
CMS Space Monitoring
During the first LHC run, CMS stored about one hundred petabytes of data. Storage accounting and monitoring help to meet the challenges of storage management, such as efficient space utilization, fair share between users and groups and resource planning. We present a newly developed CMS space monitoring system based on the storage metadata dumps produced at the sites. The information extracted from the storage dumps is aggregated and uploaded to a central database. A web based data service is provided to retrieve the information for a given time interval and a range of sites, so it can be further aggregated and presented in the desired format. The system has been designed based on the analysis of CMS monitoring requirements and experiences of the other LHC experiments. In this paper, we demonstrate how the existing software components of the CMS data placement system, PhEDEx, have been re-used, dramatically reducing the development effort.
Ratnikova, N.↗