A GNU Arch Handbook

2.3 Pick a Default Mirror Location

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You Will Probably Create Many Mirrors

When you use arch, you will create many archive mirrors.

An archive mirror is a read-only copy of a remote archive. It records a logically consistent snapshot of the remote archive. The mirror can be used for read-only purposes as a substitute for the remote archive. A mirror can be efficiently updated incrementally.

Mirrors are a robustness and performance optimization. They improve robustness by encouraging users to replicate core data with abandon. They improve performance by giving each mirror-using client a nearby copy of the data they need.

Mirrors are a Subset of Archives

There isn't much difference between mirrors and archives. An archive mirror looks and behaves much like an ordinary archive.

Put All Your Mirrors in One Place

Best practices advice: don't store your mirrors in the same place you store your archives. You'll want to treat your mirrors differently in lots of ways (e.g., backup policies). Keep local mirrors and local archives segregated.

By default, stick all of your mirrors in a single directory. Let's pretend that you choose the directory ~/mirrored-archives. Then this manual assumes that you have run:

    % mkdir ~/mirrored-archives
    % MIRROR_DIR="$(cd ~/mirrored-archives; pwd)"
    % export MIRROR_DIR

  

In other words, throughout the documentation, examples of shell commands (and similar) will use the string $MIRROR_DIR to refer to a directory in which you create your mirrors of remote archives.

Don't Be Confused!

tla does not itself use the environment variable MIRROR_DIR.

The examples in this section use an environment variable so that it can be referred to by later sections and to illustrate the best-practice that you should designate a default location for your archive mirrors.

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Copyright

Copyright (C) 2005 Tom Lord (lord@emf.net)

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this software; see the file COPYING. If not, write to the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

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