Results 1 to 2 of 2

Thread: zpaq: using local .0 to speed extract from remote .1 file

  1. #1
    Member
    Join Date
    Mar 2015
    Location
    Albuquerque
    Posts
    3
    Thanks
    0
    Thanked 3 Times in 2 Posts

    zpaq: using local .0 to speed extract from remote .1 file

    I did 'zpaq add "archive.?" files' to create archive.0 and archive.1,
    and then remote offsited archive.1, but kept archive.0 local. The
    remote machine is sshfs mounted locally.

    I now want to 'zpaq extract /mnt/sshfs/archive.1 filename', but the
    sshfs link is slow so I want to read as few bytes as possible from the
    remote machine.

    My question: can I use the local archive.0 to reduce the number of
    remote archive.1 bytes I read?

    I know archive.0 contains some information about archive.1 (eg, the
    table of contents), but is it enough to speed up extracting a file
    from archive.1?

  2. #2
    Expert
    Matt Mahoney's Avatar
    Join Date
    May 2008
    Location
    Melbourne, Florida, USA
    Posts
    3,257
    Thanks
    307
    Thanked 795 Times in 488 Posts
    The extract command doesn't read archive.0 because all of the information can be found in the index of archive.1. To read the index, it reads the 104 byte header, then seeks to the end to read the index information. It does this for each separate part (archive.2, etc). Then it reads only the data blocks that it needs to extract the requested files.

    I guess the question is how big is archive.0 and how much time would it save by reading it locally?

Similar Threads

  1. How do you extract file on MAC?
    By HIHP in forum Data Compression
    Replies: 1
    Last Post: 30th November 2011, 00:56
  2. comparing file transfer speed with ccm and lzma compression
    By Shelwien in forum Data Compression
    Replies: 19
    Last Post: 10th March 2011, 12:49
  3. How to extract a file from PMD archive?
    By atasoft in forum Data Compression
    Replies: 2
    Last Post: 2nd October 2009, 23:04
  4. Remote diff utility
    By Shelwien in forum Data Compression
    Replies: 2
    Last Post: 6th September 2009, 16:37
  5. Can't extract file from ARC file.
    By Absurd in forum Data Compression
    Replies: 3
    Last Post: 26th January 2009, 21:11

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •