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ovdb(5)
NAME
  ovdb - Overview storage method for INN

DESCRIPTION
  Ovdb is a storage method that uses the BerkeleyDB library to store overview
  data.	 It requires version 2.6.x or later of the BerkeleyDB library; it is
  known to work well with version 2.7.7.  There is also a 3.0.55, but it is
  not very stable (though ovdb will compile correctly with it).	 Check the
  web page http://www.avalon.net/~hakehoe/inn/ for the latest on BerkeleyDB
  compatibility.

  Ovdb makes use of the full transaction/logging/locking functionality of the
  BerkeleyDB environment.  BerkeleyDB may be downloaded from
  http://www.sleepycat.com .

  The BerkeleyDB distribution is (by default) installed into
  /usr/local/BerkeleyDB, with subdirectories lib/, include/, and bin/ for the
  library, headers, and support tools, respectively.  Version 3.x uses
  /usr/local/BerkeleyDB.3.x instead.  Ovdb uses some of the support tools in
  the bin/ subdirectory; namely db_archive, db_checkpoint, and db_deadlock.

INSTALLATION
  To build ovdb support into INN, specify the option `--with-berkeleydb' when
  running the configure script.	 By default, configure will search for a
  BerkeleyDB tree in several likely locations, and choose the highest version
  (based on the name of the directory, e.g., BerkeleyDB.3.0) that it finds.
  There will be a message in the configure output indicating the chosen
  pathname.

  You can override this pathname by adding a path to the option, e.g.,
  `--with-berkeleydb=/usr/BerkeleyDB.3.1'.  This directory is expected to
  have subdirectories include, lib, and bin containing db.h, the library
  itself, and the db_* utilities, respectively.

  The ovdb database will take up more disk space for a given spool than the
  other overview methods.  Plan on needing at least 1.1 KB for every article
  in your spool (not counting crossposts).  So, if you have 5 million
  articles, you'll need at least 5.5 GB of disk space for ovdb.	 With
  BerkeleyDB 2.x, the db files are 'grow only'; the library will not shrink
  them, even if data is removed.  So, reserving extra space above the
  estimate is a good idea.  Plus, you'll need additional space for
  transaction logs: at least 40 MB, preferably 100 MB or more.	(The logs may
  be on a different filesystem -- see the DB_CONFIG section.)

CONFIGURATION
  To enable ovdb, set the ovmethod parameter in inn.conf to `ovdb'.  The ovdb
  database is stored in the directory specified by the pathoverview paramter
  in inn.conf.	This is the "DB_HOME" directory.  To start out, this
  directory should be empty (other than an optional DB_CONFIG file, see the
  DB_CONFIG section for details) and innd (or makehistory) will create the
  files as necessary in that directory.

  Other parameters for configuring ovdb are in the optional ovdb.conf
  configuration file.  See also the sample ovdb.conf.

  numdbfiles
      Overview data is split between this many files.  Currently, innd will
      keep all of the files open, so don't set this too high or innd may run
      out of file descriptors.	The nnrpds only open one at a time,
      regardless.  May be set to one, or just a few, but only do that if your
      OS supports large (>2G) files.  Warning: do NOT change this on an
      already established database.  Default is 32.

  txn_nosync
      If txn_nosync is set to false, BerkeleyDB flushes the log after every
      transaction.  This minimizes the number of transactions that may be
      lost in the event of a crash, but results in significantly degraded
      performance.  Default is true.

  cachesize
      Size of the memory pool cache, in Kilobytes.  The cache will have a
      backing store file in the DB directory which will be at least as big.
      In general, the bigger the cache, the better.  Use `db_stat -m' to see
      cache hit percentages.  If they're less than 80%, try increasing the
      cache size.  To make a change of this parameter take effect with an
      existing database, remove the __db* files while there are no database
      processes running.  Default is 8000 K, which may be adequate for small
      to medium-sized servers.	Full-feed servers will probably need at least
      14000.

  pagesize
      Sets the page size for the DB files (in bytes).  Must be a power of 2.
      Best choices are 4096, 8192, or 16384.  The default is 8192.  You can
      not change the pagesize of an existing DB, it must be recreated.

  minkey
      Sets the minimum number of keys per page.	 See the BerkeleyDB
      documentation for more info.  Default is based on page size:

       default_minkey = pagesize / 2048

      You can not change the minkey of an existing DB, it must be recreated.

  DB_CONFIG

  A file called DB_CONFIG may be placed in the database directory to
  customize where the various database files and transaction logs are
  written.  By default, all of the files are written in the "DB_HOME"
  directory.  One way to improve performance is to put the transaction logs
  on a different disk.	To do this, put:

  DB_LOG_DIR /path/to/logs

  in the DB_CONFIG file.  If the pathname you give starts with a /, it is
  treated as an absolute path; otherwise, it is relative to the "DB_HOME"
  directory.  Make sure that any directories you specify exist and have
  proper ownership/mode before starting INN, because they won't be created
  automatically.  Also, don't change the DB_CONFIG file while anything that
  uses ovdb is running.

  The DB_CONFIG functionality is part of BerkeleyDB itself.

RUNNING
  You don't need to do anything special when starting or stopping INN when
  using ovdb, as long as you use rc.news.  When starting, rc.news:

  ·   Runs `ovdb_recover'.  This will perform any needed recovery on the
      database; e.g., if there was a crash that may have left the database in
      an inconsistent state.  This is done before innd is started.  If the
      innd.pid file is present but innd is not running (i.e., unclean
      shutdown), rc.news will supply the `-f' argument to `ovdb_recover'

  ·   Runs `dbprocs start'.  This starts the DB housekeeping processes.

  And when stopping INN, rc.news calls `dbprocs stop' after the other INN
  processes have been shut down.

DIAGNOSTICS
  Problems relating to ovdb are logged to news.err with "OVDB" in the error
  message.

  If a program accessing the database crashes, or otherwise exits uncleanly,
  it might leave a stale lock in the database.	This lock could cause other
  processes to deadlock on that stale lock.  To fix this, shut down all news
  processes (using `kill -9' if necessary) then run `ovdb_recover -f' as the
  news user, e.g.: `su news -c "/PATHBIN/ovdb_recover -f"' This will remove
  all locks plus repair any damage caused by killing deadlocked processes.

FILES
  inn.conf
      The ovmethod and pathoverview parameters are relevant to ovdb.

  ovdb.conf
      Optional configuration file for tuning.  See CONFIGURATION section
      above.

  pathoverview
      Directory where the database goes.  BerkeleyDB calls it the 'DB_HOME'
      directory.

  pathoverview/DB_CONFIG
      Optional file to configure the layout of the database files.

TO DO
  I've modified innshellvars and innshellvars.pl to add the BerkeleyDB bin
  dir to PATH and set DB_HOME to innconf->pathoverview.	 Since I don't know
  TCL, someone needs to modify innshellvars.tcl in the same way.

  Implement a way to limit how many databases can be open at once (to reduce
  file descriptor usage); maybe using something similar to the cache code in
  ov3.c

HISTORY
  Written by Heath Kehoe <hakehoe@avalon.net> for InterNetNews

SEE ALSO
  rc.news(8), inn.conf(5), dbprocs(8), ovdb_recover(8), ovdb_upgrade(8)

  BerkeleyDB documentation, in the docs directory of the BerkeleyDB source
  distribution, or on the Sleepycat web page: http://www.sleepycat.com/

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Alphabetical listing for O

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