Data & Storage Services

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

DSS

The Data and Storage Services Group and CASTOR

Alberto Pace

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

2

DSS group mandate

• Ensure a coherent development and operation of storage services at CERN for all aspects of physics data

• The technologies currently used to deliver these services are– CASTOR– AFS– TSM

• We have the responsibility to constantly understand and consider alternatives to these solutions– This is a very complex cost / benefit assessment– The cost and the risk of a change are high. So must be the

expected benefits

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

4

DSS organization: 3 sections

• TAB – Tape Archive and Backup– Design, operate and support the archive and backup services– This includes the tape-based software back-end for CASTOR,

tape robotics, drive and media for physics, infrastructure for backup and restore of file servers and databases

– 7 staff members• FDO – File and Disk operations

– Operate and support the storage and file system services for physics

– This includes the CASTOR and AFS services– 7 staff members

• DT – Design and Transition– Design and develop central storage services and their evolution.– This includes CASTOR and XROOT components as well as

protocols for optimal access to physics data– 6 staff members

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

5

Castor data growth

Source: Miguel Marques Coelho Dos Santos

12 million files / month

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

6

Tier-0 export

Source: Miguel Marques Coelho Dos Santos

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

7

Castor Usage (Last 2 months)

Disk Servers (Gbytes/s)

Data written to tape (Gbytes/s)

Source: Miguel Marques Coelho Dos Santos, German Cancio Melia

• 45K tape cartridges, 29K of which full• 26PB of data, 130 drives, 7 libraries

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

8

Castor Role

LHC Experiments

Tier-1s datareplication CASTOR

Disk Pools

tape servers

ASGC

BNL

FNAL

FZK

IN2P3

CNAF

NDGF

NIKHEF

PIC

RAL

TRIUMF

Analysis CPU ClustersData Reprocessing End-user analysis

ANALYSIS

AREA OFCONCERN

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

9

Areas of research & Development

LHC Experiments

Tier-1s datareplication CASTOR

tape servers

ASGC

BNL

FNAL

FZK

IN2P3

CNAF

NDGF

NIKHEF

PIC

RAL

TRIUMF

ANALYSIS

Managedon demandreplication

ScalableSecureAccountableGlobally accessibleManageableMultiple level of services-Arbitrary availability-Arbitrary reliability-Arbitrary performanceDecoupled from HW

Disk Pools

Areas of R & D

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

10

Current strategy

• Stability of service is required during the LHC operation

• Keep Castor for what it was designed for and for what it is good at– Limit developments to consolidation. Continue improving

tape reliability and efficiency for reads+writes (tape scrubbing, minimise tape recalls, developments for buffered tape marks).

• We have the responsibility to constantly understand and consider alternatives– This is a very complex cost / benefit assessment– The cost and the risk of a change are high. So must be the

expected benefits– Investigations (“Demonstrators”) are done independently

from Castor production service

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

11

Areas of developments

• In CASTOR– Consolidation in the area of Stager, Scheduler, SRM– Monitoring – Tape subsystem

• improved efficiency for reads+writes, tape scrubbing, minimise tape recalls, buffered tape marks

• “Demonstrator” Requirements– Scalable– Secure– Accountable– Globally accessible– Manageable– Multiple level of services

• Arbitrary availability, Arbitrary reliability, Arbitrary performance– Decoupled from HW

CERN IT Department

CH-1211 Genève 23

Switzerlandwww.cern.ch/

it

InternetServices

DSS

12

The Castor review agenda

• Presentations– The April 2010 incident (German)– Change and release management (Sebastien) – Operation, deployment and upgrade processes

(Miguel) – Tape operation (Vlado) – Monitoring (Dirk)

• Reviewer discussion