Future Plans at RAL Tier 1

Shaun de Witt

Introduction• Current Set-Up• Short term plans• Final Configuration• How we get there…• How we plan/hope/pray to use CEPH

Current InfrastructureCommo

n

CMSATLAS Gen LHcB

Common Services(nsd, Cupv, vmgr, vdqm)

Instances

Disk Layer(Tape and Disk ‘Pools’)

TapeLayer(at least 1 dedicated drive)

ATLAS Instance Explodednsd01

nsd02SRM01 SRM02 SRM03 SRM04

HeadNode01RH

StagerTapeGateway

HeadNode02TransferMgr

HeadNode03TransferMgr

NSDXroot Mgr

atlasTape atlasDataDisk atlasScratchDisk

Xroot proxy

x12x1

Database ConfigurationRepack

Nameserver

Cupv…

CMS SRMCMS STGR

LHCb SRMLHCb STGR ATLAS SRM ATLAS

STGRGen SRMGen STGR

RepackNameserve

rCupv

…

CMS SRMCMS STGR

LHCb SRMLHCb STGR ATLAS SRM ATLAS

STGRGen SRMGen STGR

Primaries

Standbys

DataGuard

Short Term Plans…• Improve tape cache performance for

ATLAS– Tape rates limited by disk– Currently heavy IO (read/write from

grid/tape)– Currently configured with 10(7) ‘small’

server in RAID6– Would RAID-1(0) help?

The Future

Swift/S3 XROOT/gridFTP

CASTOR

What is • Erasure-coded CEPH High-throughput

Objectstore• EC uses 16+3• ALL user data planned to use erasure

coding (no replication)• S3/SWIFT recommended interfaces

– Xroot and gridFTP for legacy support• … more later

The Plan…• Move

– The data• Modify• Merge

The ‘Plan’ – Phase 1• Current disk purchases are usable for

CEPH and classic CASTOR• Start moving atlasScratchDisk over to echo

– Lifetime of files should be ~2 weeks– Allows us to monitor production use of echo

• Work with VOs to migrate relevant data using FTS

• Maintain classic CASTOR

The Plan – Phase 2• Once all disk-only (on echo?)

– Consolidate to single castor instance• With single shared diskpool• Tape drive dedication…(Tim knows)• Clear all diskcopies• Single 2/3 node RAC + stdby

– Common headnodes supporting all services– Maintain 3-4 SRMs

• Will probably be phased in

Accessing ECHO• VOs use gridFTP and xroot ATM

– Write using 1 protocol, read using either• But not S3/SWIFT

– Proposed gridFTP url (writing?)• gsiftp://gateway.domain.name/<pool>/<file>• Steers transfer to pool• Certificate (VO and Role) for AA

– Xroot URL• As suggested by Seb…

– But what about access?

The Known Unknowns• S3/SWIFT interoperability?• Will CASTOR/CEPH support EC pools?• Partial writes verboten?• Do users need to supply• Support for CEPH plugins