AFS Administrator Guide

Project creation

 
How to ask for an AFS project space is described in KB466.
 
Once the project 'xyz' has been created, you will find it in /afs/cern.ch/project/xyz.
 
 

Basic tasks

 
The admins have full control over the project space, this includes in particular the creation/deletion
of volumes, the creation/deletion of mount points and changing quotas and ACLs.
 
The tool to manage an AFS project space is afs_admin which is installed on standard SLC machines.
'afs_admin help' will give you an overview of the available commands.
 
The most relevant operations in the beginning are:
 

Project space overview

- done with 'afs_admin list_project <project>', e.g.
  afs_admin list_project xyz
  will list the admins, the quota, the current allocation and the currently existing 
  volumes in project xyz
 

Creation of volumes and mount points

- done with 'afs_admin create <mnt> <volume>', e.g. 
  afs_admin create /afs/cern.ch/project/xyz/test1 p.xyz.test1
  will create a volume called p.xyz.test1 and mount that at /afs/cern.ch/project/xyz/test1
 
- note that you can only create volumes with names that begin with 'p.xyz.'
  and that volume names are limited to 22 characters
 

Changing quotas

- once a volume is mounted you can list its quota with 'afs_admin list_quota <path>', e.g.
  afs_admin list_quota /afs/cern.ch/project/xyz/test1
 
- you can change the quota with 'afs_admin set_quota <path>', e.g.
  afs_admin set_quota /afs/cern.ch/project/xyz/test1 5G
  would set the quota of the volume p.xyz.test1 to 5GB 
 

Changing ACLs

- you can list the ACLs of a dir with 'afs_admin list_acl <path>', e.g.
  afs_admin list_acl /afs/cern.ch/project/xyz/test1
 
- you can change the ACls with 'afs_admin set_acl <path> <access_list_entries>', e.g.
  afs_admin set_acl /afs/cern.ch/project/xyz/test1 arne read
  would give the account arne read access
 
- as the number of entries on an ACL are limited, you may want to create groups and
  puth them on the ACLs rather than individual accounts 
 
 

Deletion of volumes and mount points

- done with 'afs_admin delete <path>', e.g.
  afs_admin delete /afs/cern.ch/project/xyz/test1
  would unmount the volume and delete it
 

Add/remove project admins

- done with 'afs_admin set_acl <project> <account [none]>', e.g.
  afs_admin set_acl xyz arne
  will make 'arne' an admin for xyz, while
  afs_admin set_acl xyz arne none
  will remove 'arne' from the list of admins for project 'xyz'
 
 

Advanced features

Replication

- you can create read-only (RO) snapshots of the current content of standard (read-write, RW) volumes
 
- this can be helpful for distributing load on multiple volumes and hence multiple partitions and servers 
 
- done with 'afs_admin create_replica <volume>', e.g.  afs_admin create_replica p.xyz.test1
 
- note that this will change semantics slightly: when walking down a path AFS will always prefer the RO volume
  over the RW one
 
- if the RW volume for which RO volumes exist needs to be accessed, you can do so by using '/afs/.cern.ch/...'
  rather than '/afs/cern.ch/...'
 
- syncing the ROs from the RWs is done with 'afs_admin vos_release (<volume><path>)', e.g.
  afs_admin vos_release /afs/cern.ch/project/xyz/test1 
 

Volume parameters

- volume co-location or volume separation can be controlled via 'afs_admin set_parameter',
  see 'afs_admin help set_parameter' for a detailed description
 

Recover a project volume from backup

- KB431 describes how to retrieve earlier version of a project volume
 
 

Good to know

- all data on AFS is backed up daily and kept for 6 months

- volumes should always start with 'p.<projectname>.', e.g. 'p.xyz.'

- 'afs_admin help <subcommand>' will provide you with some help information on a subcommand,
  e.g. 'afs_admin help create' will display the help for the 'create' subcommand

- project volumes are limited in size; the reasoning is described in KB984

- the number of files per directory in AFS is limited; the reasoning is described in KB42

Getting support

The AFS support team is available via the CERN Service Portal for AFS

 

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