Difference: TiersAtRAL (2 vs. 3)

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Introduction

This page briefly explains what the ATLAS computing model is, what facilities are avaliable at RAL and how ATLAS users can access them.

Tier 0 This is CERN where the raw data will be produced. This is archived at CERN before being distributed to the Tier 1s.

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Tier 1 There are 10 Tier 1s serving ATLAS. RAL is the UK Tier 1 and is expected to recieve 10% of the raw data from CERN. Tier 1

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Tier 1 There are 10 Tier 1s serving ATLAS. RAL is the UK Tier 1 and is expected to recieve 10% of the raw data from CERN. Tier 1

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Tier 2

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Tier 2

Tier 3

This page explains the computing model and the hardware that is avaliable at RAL.

The Tier 1 for the UK cloud is based at RAL. The Tier 1 is in the machine room in building R89.

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In order to run at the Tier 1 you grid certificate must be either:

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In order to run at the Tier 1 you grid certificate must be either: /atlas/uk/Role=production /atlas/uk/Role=poweruser0

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/atlas/uk/Role=production /atlas/uk/Role=poweruser0

As well as the Tier 1 there is a Tier 2 cluster also based at RAL however it is in a different building from the Tier 1 and run by different people.

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The Tier 3 is actually part of the Tier 2 that has been reserved for use by RAL staff.

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A List of the space tokens that can be found in the Tiers of ATLAS

Space Token	Permission	Notes

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RALPP_DATADISK	default
RALPP_HOTDISK	default	Used to store an extra copy of "hot" data
RALPP_MCDISK	default
RALPP_PRODDISK	default
RALPP_SCRATCHDISK	default + everyone get write permission	Deleted after 28 days
RALPP_SOFT-TEST	default + soft-test users get write and delete permission
RALPP_LOCALGROUPDISK	default + UK users get write permission

default = '/atlas/Role=NULL': 'r---', '/atlas/Role=production' : 'rwpuda'

The Tier 3 is actually part of the Tier 2 that has been reserved for use by RAL staff.

Disk	Size	Backed Up	Usage
$HOME	1 GB*	Yes	Personal files
/opt/ppd/atlas	128 GB	Mirrored ever 12 hours	ATLAS group usage
/opt/ppd/scratch	1.6 TB	No	Data - An email will be sent reminding you to delete files
/opt/ppd/month	1.6 TB	No	Data - An email will be sent reminding you to delete files

*The initial allowance is 2MB but this is a soft cap and will be removed if you send an email to Chris Brew.

As well as access to local disk space RAL users will also have access to the space tokens avaliable on the Tier 2.

-- AlastairDewhurst - 2009-10-09