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AFS at CERN and other High Energy Physics Sites

AFS at CERN and other High Energy Physics Sites. Rainer Többicke / CERN. AFS Software. Servers: OpenAFS 1.2.6 Focus: stability Additional patches Local debugging Clients: OpenAFS 1.2.7 Linux RPMs Historical accumulation: wide spread of partly ancient versions … and system architectures.

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AFS at CERN and other High Energy Physics Sites

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  1. AFS at CERN and other High Energy Physics Sites Rainer Többicke / CERN

  2. AFS Software • Servers: OpenAFS 1.2.6 • Focus: stability • Additional patches • Local debugging • Clients: OpenAFS 1.2.7 • Linux RPMs • Historical accumulation: wide spread of partly ancient versions • … and system architectures Rainer Többicke / CERN

  3. Service • Total disk space: • ~ 10 TB installed • ~ 6 TB usable • 15 Sun Servers, 10 PC servers • Sun A1000 RAID (-5) Systems • Clients • 4000-6000 • 2000 off-site Rainer Többicke / CERN

  4. Usage • Private user files - home directories • 14000 users, 5000 active, 2TB disk space • Scratch • “low quality” space at descretion of major user groups, ~ 1 TB disk space • Software development • Production environment • Software • Controlled by major user groups Rainer Többicke / CERN

  5. Evolution: # of users Rainer Többicke / CERN

  6. Evolution: User space Rainer Többicke / CERN

  7. Evolution: Project space Rainer Többicke / CERN

  8. The Future of AFS • History • Characteristics • What do we require? • Distributed file systems Rainer Többicke / CERN

  9. History • IBM sponsored development at CMU in the late 80s • Transarc Corporation, later owned by IBM • Strong academic (CMU, MIT, Umich) user community • AFS 3.2 Introduced @ CERN in 1993 • Now almost ubiquitous in HEP • OpenAFS - open source as of 2000 • Active development – 4-5 releases/year • Alternative implementations: Arla, Red Hat • Prime time quality software Rainer Többicke / CERN

  10. AFS characteristics • Global file system • Security, flexibilty • NAS approach • No special infrastructure • Moderate performance – single path to data • Performance (in 2002) for big files • Slightly below NFS with caching: 20-25 MB/s • approaching RFIO without caching: ~30 MB/s Rainer Többicke / CERN

  11. AFS characteristics – cont’d • Scaling • Number of files in a directory ~ 62000 • 2 GB file size limit • No single directory bigger than a “disk” • AFS cache size? • Scaling – non-issues • Number of servers • Performance limits • No file striping – file access limited by single server • Client disk caching • Flat client/server topology, no proxies or cascades Rainer Többicke / CERN

  12. Global access Cascading / proxies? Security / access control Manageability Performance infrastructure files data files Scalability Cost Standard in AFS Kerberos, ACLs AFS volumes … OK problematic Looks OK Free Requirements ? Rainer Többicke / CERN

  13. Distributed File Systems • Production, IP (NAS) • NFS V3, V4 • Microsoft Dfs • SAN based • GFS, CXFS • GPFS • Recent Developments • Lustre, Intermezzo , StorageTank •  PASTA III (2002) “Distributed File Systems” Rainer Többicke / CERN

  14. Summary • From a shaky “interesting idea” in 1993 AFS has grown to a stable system • There is a need for a distributed file system for LCG • Characteristics? Rainer Többicke / CERN

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