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Accessing Storage and Copies in Storage

Accessing Storage

Accessing storage is most easily done from an LC production machine but can be done from non-LC machines and from offsite in some circumstances.

When onsite, NFT, FTP, HSI, and Hopper can be used to transfer between and LC production host and storage. If onsite but not on an LC production host, use FTP or Hopper to transfer files to or from storage.

Offsite users may access storage only if connected to the LC network via a VPN client or if their network has a trust relationship with LC's network. See https://access.llnl.gov/ for information regarding VPN. See Access Information for access prerequisites and additional information about accessing LC systems. Offsite users are limited to FTP and Hopper for accessing storage.

Copies in Storage

Some files may be so important to your project that you want to store separate, duplicate copies on independent storage media. LC's Open Computing Facility (OCF) and Secure Computing Facility (SCF) storage systems offer such dual-copy storage using the "class of service" (COS) concept.

The storage server(s) assign a COS to every incoming file based on the file's size and the client that writes it:

  • Files written with FTP, NFT, or HSI that are smaller than 256 MB are automatically assigned a COS that provides two separate copies on separate storage tapes. For these files you never need to request duplicate storage.
  • Files written with FTP, NFT, or HSI that are 256 MB or larger are assigned a COS that stores only a single copy. For mission critical files in this category you can request dual-copy storage by using the FTP command

    site dualcopy

    or the NFT command

    dualcopy

    or the HSI command

    set cos=dualcopy

before you put the large file(s) into HPSS. NFT's dir command (if used with the -h option) reports the current COS for already stored files.

  • Files written with Hopper and HTAR, regardless of their size, always get a default COS that stores only a single copy. For mission critical files written with Hopper, you can request dual-copy storage for a Hopper session (the setting does not persist beyond a session) by setting HPSS Class of Service to Dual-Copy (under File, Preferences, General, HPSS).
    For mission critical files written with HTAR you can request dual-copy storage by using the command

     -Y dualcopy

    on the HTAR execute line that creates your stored archive.

For more COS technical details, consult the SETCOS section of LC's NFT Reference Manual.