DCache Workshop

Authors

Christoph Mitterer, Oleg Tsigenov, Cesare Delle Fratte, Luca Mazzaferro, Christian Bernardt

Abstract

dCache is one of the most used storage solutions in the WLCG consisting of over 94 PB of storage distributed world wide on >77 sites. Depending on the Persistency Model, dCache provides methods for exchanging data with backend (tertiary) Storage Systems as well as space management, pool attraction, dataset replication, hot spot determination and recovery from disk or node failures. Beside HEP specific protocols, data in dCache can be accessed via NFSv4.1 (pNFS) as well as through WebDav. dCache has steadily improved its functionality up to the point that we are becoming the DESY storage cloud provider. This means that dCache users can now access data using the OwnCloud client software with its synchronisation functionality. In addition to that users can access their data by using the same user over NFSv41, WebDAV and gridFTP, which allows for a wide range of use cases from traditional HEP storage to even HPC application.

The workshop includes theoretical sessions and practical hands-on sessions such as installation, configuration of its components, simple usage and monitoring. The basic knowledge of Unix systems is required. Please familiarise yourself with a Linux terminal and the peculiarities of a linux text editor (vi, emacs etc.).

Necessities

We would like to ask every participant to bring a notebook that has an ssh client installed. Please check on your machine.

Linux and MacOS machines most of the time have an ssh client installed. Please check. Windows machine users can install a putty client (​http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe).

Event

Thursday, September 4 2014, 10:50-18:30

Time Table

10:50	Welcome And Overview, held by Christoph Mitterer A welcome and overview to the course.
10:55	Introduction To dCache, held by Christoph Anton Mitterer Gives an overview on dCache, its history, future and application areas, its basic functionality and special features, its structure, main components, databases, protocols and data access model as well as typical cluster setups.
11:35	Puppet, held by Luca Mazzaferro
11:45	dCache and Puppet, held by Cesare Delle Fratte
11:55	[dCache Installation with Puppet], held by Cesare Delle Fratte and Luca Mazzaferro Last year we described the typical installation-procedure for a dCache cluster, including its external dependencies, the core-services and the file hierarchy provider, the creation of pools as well as the configuration system. This year this procedure will be done using puppet. Luca and Cesare will guide you through the process.
12:20	Lunch
13:30	dCache Within Grids, held by Christoph Anton Mitterer Gives some brief notes on grid-specific concepts, techniques, tools and clients that are important for using dCache within a grid (for example the LCG) and that will be referenced in later chapters.
13:40	gPLazma, held by Christoph Anton Mitterer
14:00	[Writing to / Reading From dCache], held by Oleg Tsigenov Shows two typical access methods using WebDAV http and https access. It explains how to setup dCache to get unauthorised and authorised access to dCache. The use of x509 certificates is also explained.
15:30	Coffee break
16:00	Pool Management - Theoretical insides held by Oleg Tsigenov
16:30	Pool Management And Pool Selection , held by Oleg Tsigenov Covers some of the concepts and means of selecting pools for client read- and write-accesses as well as their configuration.
17:30	Updating dCache using puppet , held by Cesare Delle Fratte and Luca Mazzaferro Having installed dCache using puppet one of course also wants to update dCache in the same way. Cesare and Luca will also provide you with a how-to.
17:50	Buffer + Bonus parts
18:30	End of the workshop

Assigned excercise machines

UID             Host name                    IP address

Links

The dcache.org main page is the starting point for all interests about dCache. Either searching for documentation or support, news or source code, everything can be found there.

Acknowledgement

Thank you German Support Team. A special thanks to D-Grid and the HGF-Alliance Physics on the Terascale for funding.