git-annex comes with some built-in preferred content settings, that can be used with repositories that are in special groups. To make a repository use one of these, just set its preferred content expression to "standard", and put it in one of these groups. For example, to put the current repository in the manual group and use this group to control the preferred content, run

git annex wanted . standard
git annex group . manual

In the webapp, just edit the repository and select the group.

(Note that most of these standard expressions also make the repository want to get any content that is only currently available on untrusted and dead repositories. So if an untrusted repository gets connected, any repository that can will back it up.)

The following standard groups are available:

client

All content in the current working tree is wanted, unless it's for a file in a "archive" directory, which has reached an archive repository.

(include=* and ((exclude=*/archive/* and exclude=archive/*) or (not (copies=archive:1 or copies=smallarchive:1)))) or approxlackingcopies=1

transfer

Use for repositories that are used to transfer data between other repositories, but do not need to retain data themselves. For example, a repository on a server, or in the cloud, or a small USB drive used in a sneakernet.

The preferred content expression for these causes them to get and retain data until all clients have a copy.

not (inallgroup=client and copies=client:2) and ($client)

(Where $client is a copy of the preferred content expression used for clients.)

The "copies=client:2" part of the above handles the case where there is only one client repository. It makes a transfer repository speculatively prefer content in this case, even though it as of yet has nowhere to transfer it to. Presumably, another client repository will be added later.

backup

All content is wanted. Even content of old/deleted files.

anything

incrementalbackup

Only wants content that's not already backed up to another backup or incremental backup repository.

((not copies=backup:1) and (not copies=incrementalbackup:1)) or approxlackingcopies=1

smallarchive

Only wants content that's located in an "archive" directory, and only if it's not already been archived somewhere else.

((include=*/archive/* or include=archive/*) and not (copies=archive:1 or copies=smallarchive:1)) or approxlackingcopies=1

archive

All content is wanted, unless it's already been archived somewhere else.

(not (copies=archive:1 or copies=smallarchive:1)) or approxlackingcopies=1

Note that if you want to archive multiple copies (not a bad idea!), you can set git-annex groupwanted archive to a version of the above preferred content expression with a larger number of copies than 1. Then make the archive repositories have a preferred content expression of "groupwanted" in order to use your modified version.

source

Use for repositories where files are often added, but that do not need to retain files for local use. For example, a repository on a camera, where it's desirable to remove photos as soon as they're transferred elsewhere.

The preferred content expression for these causes them to only retain data until a copy has been sent to some other repository.

not (copies=1)

manual

This gives you nearly full manual control over what content is stored in the repository. This allows using the assistant without it trying to keep a local copy of every file. Instead, you can manually run git annex get, git annex drop, etc to manage content. Only content that is already present is wanted.

The exception to this manual control is that content that a client repository would not want is not wanted. So, files in archive directories are not wanted once their content has reached an archive repository.

present and ($client)

(Where $client is a copy of the preferred content expression used for clients.)

public

This is used for publishing information to a repository that can be publically accessed. Only files in a directory with a particular name will be published. (The directory can be located anywhere in the repository.)

inpreferreddir

The name of the directory can be configured using git annex enableremote $remote preferreddir=$dirname

unwanted

Use for repositories that you don't want to exist. This will result in any content on them being moved away to other repositories. (Works best when the unwanted repository is also marked as untrusted or dead.)

not anything