NAME¶
storage.conf - Configuration file for storage manager
DESCRIPTION¶
The file
pathetc/storage.conf contains the rules to be used in assigning
articles to different storage methods. These rules determine where incoming
articles will be stored.
The storage manager is a unified interface between INN and a variety of
different storage methods, allowing the news administrator to choose between
different storage methods with different trade-offs (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. Note that you may also want to see
the options provided in
inn.conf(5) regarding article storage.
The
storage.conf 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 which 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 one
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 enclosed in double
quotes (""). If either a number sign ("#") or a double
quote 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 which
match the rules of this entry. The currently available storage methods are:
cnfs
timecaf
timehash
tradspool
trash
See the "STORAGE METHODS" section below for more details.
The meanings of the keys in each storage method entry are as follows:
- class: <storage_class>
- An identifier for this storage method entry. <storage_class> should
be a number between 0 and 255. It should be unique across all of the
entries in this file. It is mainly used for specifying expiration times by
storage class as described in expire.ctl(5); "timehash"
and "timecaf" will also set the top-level directory in which
articles accepted by this storage class are stored. The assignment of a
particular number to a storage class is arbitrary but permanent (since it
is used in storage tokens). Storage classes can be for instance numbered
sequentially in storage.conf.
- newsgroups: <wildmat>
- What newsgroups are stored using this storage method. <wildmat> is a
uwildmat(3) pattern which 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 the 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: articles crossposted to poisoned
newsgroups will not be stored using this storage method. 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: <minsize>[,<maxsize>]
- A range of article sizes (in bytes) which 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 to be stored in this storage method (if, of course, these
articles fulfill all the other requirements of this storage method entry).
By default, <minsize> is set to 0.
- expires: <mintime>[,<maxtime>]
- A range of article expiration times which 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 to say, 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, but 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 you do not want to store articles
according to their Expires: header, if any.
A <mintime> value greater than "0s" implies that this
storage method won't match any article without an Expires: header.
- options: <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: <bool>
- If this key is set to true, all the newsgroups in the Newsgroups: header
of incoming articles will be examined to see if they match newsgroups
patterns. (Normally, any non-zero number of matching newsgroups is
sufficient, provided no newsgroup matches a poison wildmat as described
above.) This is a boolean value; "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 does not match any entry, either by being posted to a newsgroup
which does not 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. 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.
STORAGE METHODS¶
Currently, there are five 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). 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 the 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 subtleties 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.
Advantages: 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. Unlike all other storage methods, it
does not require manual article expiration. With CNFS, the server will
never throttle itself due to a full spool disk, and groups are restricted
to just the buffer files given so that they can never use more than the
amount of disk space allocated to them.
Disadvantages: Article retention times are more difficult to control because
old articles are overwritten automatically. Attacks on Usenet, such as
flooding or massive amounts of spam, can result in wanted articles
expiring much faster than intended (with no warning).
- 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>/timecaf-nn/bb/aacc.CF
where "nn" is the hexadecimal value of <storage_class>,
"bb" and "aacc" are the 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 has to run periodically
to delete old articles). EXPENSIVESTAT is false for this method.
Advantages: It is roughly four times faster than "timehash" for
article writes, since much of the file system overhead is bypassed, while
still retaining the same fine control over article retention time.
Disadvantages: Using this method means giving up all but the most careful
manually fiddling with the article spool; in this aspect, it looks like
"cnfs". As one of the newer and least widely used storage types,
"timecaf" has not been as thoroughly tested as the other
methods.
- 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>/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.
Advantages: Heavy traffic groups do not cause bottlenecks, and a fine
control of article retention time is still possible.
Disadvantages: The ability to easily find all articles in a given newsgroup
and manually fiddle with the article spool is lost, and INN still suffers
from speed degradation due to file system overhead (creating and deleting
individual files is a slow operation).
- tradspool
- Traditional spool, or "tradspool", is the traditional news
article storage format. Each article is stored in an individual text file
named:
<patharticles>/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.
Advantages: It is widely used and well-understood; it can read article
spools written by older versions of INN and it is compatible with all
third-party INN add-ons. This storage mechanism provides easy and direct
access to the articles stored on the server and makes writing programs
that fiddle with the news spool very easy, and gives fine control over
article retention times.
Disadvantages: It takes a very fast file system and I/O system to keep up
with current Usenet traffic volumes due to file system overhead. Groups
with heavy traffic tend to create a bottleneck because of inefficiencies
in storing large numbers of article files in a single directory. It
requires a nightly expire program to delete old articles out of the news
spool, a process that can slow down the server for several hours or
more.
- 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.
EXAMPLES¶
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 did not 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.
As for poison wildmat expressions, if you have for instance an article
crossposted between misc.foo and misc.bar, the pattern:
misc.*,!misc.bar
will match that article whereas the pattern:
misc.*,@misc.bar
will not match that article. An article posted only to misc.bar will fail to
match either pattern.
Usually, high-volume groups and groups whose articles do not need to be kept
around very long (binaries groups, *.jobs*, news.lists.filters, etc.) are
stored in CNFS buffers. Use the other methods (or CNFS buffers again) for
everything else. However, it is as often as not most convenient to keep in
"tradspool" special hierarchies like local hierarchies and
hierarchies that should never expire or through the spool of which you need to
go manually.
HISTORY¶
Written by Katsuhiro Kondou <kondou@nec.co.jp> for InterNetNews. Rewritten
into POD by Julien Elie.
$Id: storage.conf.pod 8357 2009-02-27 17:56:00Z iulius $
SEE ALSO¶
cycbuff.conf(5),
expire.ctl(5),
expireover(8),
inn.conf(5),
innd(8),
uwildmat(3).