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AFS Update

AFS Update. O. Le Moigne IT/PDP/DM Olivier.Le.Moigne@cern.ch 1/11/99. IT/PDP/DM Section. Section leader : H.Renshall, O.Barring Tape infrastructure unit led by C.Curran F.Collin, R.Minchin SHIFT and CASTOR software unit led by J-P. Baud O.Barring, J-D.Durand

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AFS Update

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  1. AFS Update O. Le Moigne IT/PDP/DM Olivier.Le.Moigne@cern.ch 1/11/99

  2. IT/PDP/DM Section • Section leader : H.Renshall, O.Barring • Tape infrastructure unit led by C.Curran • F.Collin, R.Minchin • SHIFT and CASTOR software unit led by J-P. Baud • O.Barring, J-D.Durand • Commercial products services (HPPS and AFS) unit led by H.Renshall • B.Antoine, D.Asbury, O.Le Moigne

  3. AFS dependencies • server hardware/OS • AFS server process • Network • AFS client software (cache manager) • client hardware/OS • application

  4. AFS hardware • 33 servers • 9 IBM (AIX) • 7 SUNs (Solaris) • 17 PCs (Solaris, Linux) • disk space : 2TB available • user : 600 GB used / 1100 GB alloc • project : 800 GB used / 1400 GB alloc

  5. Disk policy • Home directories (managed by xspaceadm) • limited to 300 MB/user • mirror or RAID 5 • Project space (managed by afs_admin) • several 100GB/experiment • NO MIRROR or RAID 5 • backed up : if one disk fails, data of the day before will be recovered from tapes • or not backed up (scratch volumes : q.*)

  6. AFS software • Current version : AFS 3.4a (UNIXes, NT) • AFS 3.5 • mainly for performance improvement • deployed only for Linux • AFS 3.6 : beta under test • volumes > 2GB, Solaris 64 bits • will be deployed next year

  7. Cache Manager problems • 2 problems : • Cache consistency : a modification is not visible everywhere • Cache corruption : a file is corrupted • Solution • fs flush/flushv discouraged • should be reported to afs.support@cern.ch • new patch to be installed soon on HP nodes

  8. Other problems • Performance • Overloaded servers (eg: ASIS volumes moved) • Backups • Connectivity problem • specially with FDDI • Servers crashes (need for supported config) • Disk failures (need for redundancy)

  9. Replication • Volumes can be read-only replicated on several servers • load balancing • no trouble for clients if one server crashes • good for everything that is accessed a lot and not modified often: • binaries • documentation • give us proposal

  10. Linux • Version certified by IT/DIS : Redhat 5.1 using old free client from MIT (AFS 3.3) • stability problems (specially on SMP) • lots of cache consistency/corruption problems • completely unsupported (no pb investigation) • Supported version : Redhat 6.0, AFS 3.5 (Redhat 6.1 soon)

  11. Plans • Update hardware : homogeneity/stability • SUN Solaris • user : mirror or RAID 5 • project : all in mirror or RAID 5 ? • PC Linux : replica + scratch • Ethernet (100Mb/s or 1Gb/s) • Update software • AFS 3.6 next year • rethinking user workspace

  12. Contact • User problem • Atlas group administrator (quota) • Helpdesk@cern.ch and Atlas support list • Administration problem • Afs.Support@cern.ch and Atlas support list • Info • http://consult.cern.ch/services/afs

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