Dovecot Filesystems

Dovecot's lib-fs is a simplified API to access filesystems and databases that can be made to look similar to filesystems. It is similar to dictionary but generally where dictionary is generally used for small data fs is used for larger data.

Currently supported FS drivers are:

Name	Description
posix	POSIX filesystem.
dict	Dictionary (lib-dict wrapper).
s3	S3 object storage.
aws-s3	AWS S3 object storage.
sproxyd	Scality (sproxyd) object storage.

Wrapper drivers used on top of other drivers:

Name	Description
metawrap	File metadata.
crypt	File encryption.
compress	File compression.
dictmap	Use dict for file listings.
fscache	Local file cache.
fts_cache	Local FTS cache.

FS Settings

fs

Default	[None]
Value	Named List Filter
See Also	Dovecot Filesystems fs_name fs_driver

Create a new fs to the list of filesystems. The filter name refers to fs_name setting.

Example:

fs posix {
  # ...
}

Since an empty fs_driver default to fs_name there is no need to specify fs_driver explicitly.

It's possible to specify the same fs multiple times by separating the fs_name and fs_driver settings:

fs compress1 {
  fs_driver = compress
}
fs compress2 {
  fs_driver = compress
}

fs_driver

Default	fs_name
Value	string
See Also	fs fs_name

The fs driver to use. Defaults to fs_name.

fs_name

Default	[None]
Value	string
See Also	fs fs_driver

Name of the fs. The fs_driver setting default to this.

POSIX Filesystem

Regular POSIX filesystem. It can also be used with NFS. It doesn't support file metadata, in case you have a need for that use fs: Metawrap Filesystem.

Settings

fs_posix_accurate_mtime

Default	no
Value	boolean
Advanced Setting; this should not normally be changed.

Configure whether utimes() is called after writes to guarantee microsecond precision timestamps for files. By default Linux updates the mtime only on timer interrupts, which is not remotely close to microsecond precision.

fs_posix_autodelete_empty_directories

Default	no
Value	boolean
Advanced Setting; this should not normally be changed.

If the last file in a directory is deleted, should the parent directory be automatically deleted?

INFO

Using this setting makes the POSIX filesystem behave more like an object storage would.

WARNING

This setting can cause the POSIX filesystem to also delete the parent directory hierarchy farther up than anticipated.

fs_posix_fsync

Default	yes
Value	boolean

Configure whether fsync() is called after writes to guarantee that the file is written to disk.

fs_posix_lock_method

Default	flock
Value	string
Allowed Values	flockdotlock
Advanced Setting; this should not normally be changed.

Lock method to use for locking files. Currently nothing uses lib-fs locking.

fs_posix_mode

Default	0600
Value	octal unsigned integer

Mode to use for creating files.

fs_posix_prefix

Default	[None]
Value	string

Directory prefix where files are read from/written to.

INFO

The trailing / is not automatically added, so using e.g. /tmp/foo as prefix will cause /tmp/foofilename to be created.

Dictionary Filesystem

This is a wrapper for lib-dict for using dictionary drivers as fs drivers.

Settings

fs_dict_value_encoding

Default	raw
Value	string
Allowed Values	rawhexbase64

How to encode file contents into the dict value.

Metawrap Filesystem

This is a wrapper for other fs drivers that don't support metadata. The metadata is implemented by placing them into the beginning of the file content.