storage.conf - configuration file for storage manager

The storage manager is a unified interface between INN and a variety of different storage method, allowing the news administrator to choose between different storage methods with different tradeoffs (or even use several at the same time for different newsgroups, or articles of different sizes). The rest of INN need not care what type of storage method was used for a given article; the storage manager will figure this out automatically when that article is retrieved via the storage API.

The <pathetc in inn.conf>/storage.conf file contains the rules to be used in assigning articles to different storage methods.

The file consists of a series of storage method entries. Blank lines and lines beginning with a number sign (``#'') are ignored. The maximum number of characters in each line is 255. The order of entries in this file is important, see below.

Each entry specifies a storage method and a set of rules. Articles that match all of the rules of a storage method entry will be stored using that storage method; if an article matches multiple storage method entries, the first will be used. Each entry is formatted as follows:

method <methodname> { class: <storage_class> newsgroups: <wildmat> size: <minsize>[,<maxsize>] expires: <mintime>[,<maxtime>] options: <options> exactmatch: <bool> }

If spaces or tabs are included in a value, that value must be quoted with ``"''. If either ``#'' or ``"'' are meant to be included verbatim in a value, they should be escaped with ``\''.

<methodname> is the name of a storage method to use for articles that match the rules of this entry. The currently available storage methods are ``timecaf'', ``timehash'', ``cnfs'', ``tradspool'' and ``trash''. See the STORAGE METHODS section below for more details.

The meanings of the keys in each entry are as follows:

class

An identifier for this storage method entry. <storage_class> should be a number and should be unique across all of the entries in this file. It's used mainly for specifying expiration times by storage class as described in expire.ctl(5).

newsgroups

What newsgroups are stored using this storage method. <wildmat> is a uwildmat(3) pattern that is matched against the newsgroups an article is posted to. If ``storeonxref'' in inn.conf is ``true'', this pattern will be matched against the newsgroup names in the ``Xref'' header; otherwise, it will be matched against newsgroup names in the ``Newsgroups'' header (see inn.conf(5) for discussion of the differences between these possibilities). Poison wildmat expressions (expressions starting with ``@'') are allowed and can be used to exclude certain group patterns. ``!'' cannot be used, however. The <wildmat> pattern is matched in order. There is no default newsgroups pattern; if an entry should match all newsgroups, use an explicit ``newsgroups: *''.

size

A range of article sizes (in bytes) that should be stored using this storage method. If <maxsize> is ``0'' or not given, the upper size of articles is limited only by ``maxartsize'' in inn.conf. The ``size'' field is optional and may be omitted entirely if you want articles of any size (that otherwise fulfill the requirements of this storage method entry) to be stored in this storage method.

expires

A range of article expiration times that should be stored using this storage method. Be careful; this is less useful than it may appear at first. This is based only on the ``Expires'' header of the article, not on any local expiration policies or anything in expire.ctl! If <mintime> is non-zero, then this entry will not match any article without an ``Expires'' header. This key is therefore only really useful for assigning articles with requested longer expire times to a separate storage method. Articles only match if the time until expiration (that is, the amount of time into the future that the ``Expires'' header of the article requests that it remain around) falls in the interval specified by <mintime> and <maxtime>. The format of these parameters is 0d0h0m0s (days, hours, minutes, and seconds into the future). If <maxtime> is ``0s'' or is not specified, there is no upper bound on expire times falling into this entry (note that this key has no effect on when the article will actually be expired, only on whether or not the article will be stored using this storage method). This field is also optional and may be omitted entirely if all articles with or without an ``Expires'' header (that otherwise fulfill the requirements of this storage method entry) should be stored according to it.

options

This key is for passing special options to storage methods that require them (currently only ``cnfs''). See the STORAGE METHODS section below for a description of its use.

exactmatch

If this key is set to ``true'', all newsgroups will be examined to see if they match newsgroups patterns. (Normally, any nonzero number of matching newsgroups is sufficient, provided no newsgroup matches a poison wildmat as described above.) This is a boolan value and ``true'', ``yes'' and ``on'' are usable to enable this key. The case of these values is not significant. The default is false.

If an article matches all of the constraints of an entry, it is stored via that storage method and is associated with that <storage_class>. This file is scanned in order and the first matching entry is used to store the article.

If an article doesn't match any entry, either by being posted to a newsgroup that doesn't match any of the <wildmat> patterns or by being outside the size and expires ranges of all entries whose newsgroups pattern it does match, the article is not stored and is rejected by innd(8). When this happens, the error message

cant store article: no matching entry in storage.conf

is logged to syslog. If you want to silently drop articles matching certain newsgroup patterns or size or expires ranges, assign them to the ``trash'' storage method rather than having them not match any storage method entry.

Currently, there are four storage methods available. Each method has its pros and cons; you can choose any mixture of them as is suitable for your environment. Note that each method has an attribute ``EXPENSIVESTAT'' which indicates whether checking the existence of an article is expensive or not. This is used to run expireover(8).

cnfs

The ``cnfs'' storage method stores articles in large cyclic buffers (CNFS stands for Cyclic News File System). It's by far the fastest of all storage methods (except for ``trash''), since it eliminates the overhead of dealing with a file system and creating new files. Articles are stored in CNFS buffers in arrival order, and when the buffer fills, it wraps around to the beginning and stores new articles over top of the oldest articles in the buffer. The expire time of articles stored in CNFS buffers is therefore entirely determined by how long it takes the buffer to wrap around, which depends on how quickly data is being stored in it. (This method is therefore said to have self-expire functionality.) ``EXPENSIVESTAT'' is ``false'' for this method. CNFS has its own configuration file, cycbuff.conf, which describes some subtlties to the basic description given above. Storage method entries for the ``cnfs'' storage method must have an ``options'' field specifying the metacycbuff into which articles matching that entry should be stored; see cycbuff.conf(5) for details on metacycbuffs.

timecaf

This method stores multiple articles in one file, whose name is based on the article's arrival time and the storage class. The file name will be <patharticles in inn.conf>/timecaf-nn/bb/aacc.CF, where ``nn'' is the hexadecimal value of <storage_class>, ``bb'' and ``aacc'' are hexadecimal components of the arrival time, and ``CF'' is a hardcoded extension. (The arrival time, in seconds since the epoch, is converted to hexadecimal and interpreted as 0xaabbccdd, with ``aa'', ``bb'', and ``cc'' used to build the path.) This method does not have self-expire functionality (meaning expire(8) has to run periodically to delete old articles). ``EXPENSIVESTAT'' is ``false'' for this method.

timehash

This method is very similar to ``timecaf'' except that each article is stored in a separate file. The name of the file for a given article will be <patharticles in inn.conf>/time-nn/bb/cc/yyyy-aadd, where ``nn'' is the hexadecimal value of <storage_class>, ``yyyy'' is a hexadecimal sequence number, and ``bb'', ``cc'', and ``aadd'' are components of the arrival time in hexadecimal (the arrival time is interpreted as documented above under ``timecaf''). This method does not have self-expire functionality. ``EXPENSIVESTAT'' is ``true'' for this method.

tradspool

Traditional spool, or ``tradspool'', is the traditional news article storage format. Each article is stored in a file named: <patharticles in inn.conf>/news/group/name/nnnnn, where ``news/group/name'' is the name of the newsgroup to which the article was posted with each period changed to a slash, and ``nnnnn'' is the sequence number of the article in that newsgroup. For crossposted articles, the article is linked into each newsgroup to which it is crossposted (using either hard or symbolic links). This is the way versions of INN prior to 2.0 stored all articles, as well as being the article storage format used by C News and earlier news systems. This method does not have self-expire functionality. ``EXPENSIVESTAT'' is ``true'' for this method.

trash

This method silently discards all articles stored in it. Its only real uses are for testing and for silently discarding articles matching a particular storage method entry (for whatever reason). Articles stored in this method take up no disk space and can never be retrieved, so this method has self-expire functionality of a sort. ``EXPENSIVESTAT'' is ``false'' for this method.

The following sample storage.conf file would store all articles posted to alt.binaries.* in the ``BINARIES'' CNFS metacycbuff, all articles over roughly 50 KB in any other hierarchy in the ``LARGE'' CNFS metacycbuff, all other articles in alt.* in one timehash class, and all other articles in any newsgroups in a second timehash class, except for the internal.* hierarchy which is stored in traditional spool format.

method tradspool { class: 1 newsgroups: internal.* }

method cnfs { class: 2 newsgroups: alt.binaries.* options: BINARIES }

method cnfs { class: 3 newsgroups: * size: 50000 options: LARGE }

method timehash { class: 4 newsgroups: alt.* }

method timehash { class: 5 newsgroups: * }

Notice that the last storage method entry will catch everything. This is a good habit to get into; make sure that you have at least one catch-all entry just in case something you didn't expect falls through the cracks. Notice also that the special rule for the internal.* hierarchy is first, so it will catch even articles crossposted to alt.binaries.* or over 50 KB in size.

Written by Katsuhiro Kondou <kondou@nec.co.jp> for InterNetNews.

cycbuff.conf(5), expire.ctl(5), inn.conf(5), innd(8), newsfeeds(5), uwildmat(3).