2 # Copyright 2007 The OpenLDAP Foundation, All Rights Reserved.
3 # COPYING RESTRICTIONS APPLY, see COPYRIGHT.
7 System Administration is all about maintenance, so it is only fair that we
8 discuss how to correctly maintain an OpenLDAP deployment.
15 You can use {{slapcat}}(8) to generate an LDIF file for each of your {{slapd}}(8)
16 back-bdb or back-hdb databases.
18 > slapcat -f slapd.conf -b "dc=example,dc=com"
20 For back-bdb and back-hdb, this command may be ran while slapd(8) is running.
27 Berkeley DB log files grow, and the administrator has to deal with it. The
28 procedure is known as log file archival or log file rotation.
30 Note: The actual log file rotation is handled by the Berkeley DB engine.
32 Logs of current transactions need to be stored into files so that the database
33 can be recovered in the event of an application crash. Administrators can change
34 the size limit of a single log file (by default 10MB), and have old log files
35 removed automatically, by setting up DB environment (see below). The reason
36 Berkeley DB never deletes any log files by default is that the administrator
37 may wish to backup the log files before removal to make database recovery
38 possible even after a catastrophic failure, such as file system corruption.
40 Log file names are {{F:log.XXXXXXXXXX}} (X is a digit). By default the log files
41 are located in the BDB backend directory. The {{F:db_archive}} tool knows what
42 log files are used in current transactions, and what are not. Administrators can
43 move unused log files to a backup media, and delete them. To have them removed
44 automatically, place set_flags {{DB_LOG_AUTOREMOVE}} directive in {{F:DB_CONFIG}}.
46 Note: If the log files are removed automatically, recovery after a catastrophic
47 failure is likely to be impossible.
49 The files with names {{F:__db.001}}, {{F:__db.002}}, etc are just shared memory
50 regions (or whatever). These ARE NOT 'logs', they must be left alone. Don't be
51 afraid of them, they do not grow like logs do.
53 To understand the {{F:db_archive}} interface, the reader should refer to
54 chapter 9 of the Berkeley DB guide. In particular, the following chapters are
57 * Database and log file archival
62 Advanced installations can use special environment settings to fine-tune some
63 Berkeley DB options (change the log file limit, etc). This can be done by using
64 the {{F:DB_CONFIG}} file. This magic file can be created in BDB backend directory
65 set up by {{slapd.conf}}(5). More information on this file can be found in File
66 naming chapter. Specific directives can be found in C Interface, look for
67 {{DB_ENV->set_XXXX}} calls.
69 Note: options set in {{F:DB_CONFIG}} file override options set by OpenLDAP.
70 Use them with extreme caution. Do not use them unless You know what You are doing.
72 The advantages of {{F:DB_CONFIG}} usage can be the following:
74 * to keep data files and log files on different mediums (i.e. disks) to improve
75 performance and/or reliability;
76 * to fine-tune some specific options (such as shared memory region sizes);
77 * to set the log file limit (please read Log file limits before doing this).
79 To figure out the best-practice BDB backup scenario, the reader is highly
80 recommended to read the whole Chapter 9: Berkeley DB Transactional Data Store Applications.
81 This chapter is a set of small pages with examples in C language. Non-programming
82 people can skip this examples without loss of knowledge.
89 If you put "checkpoint 1024 5" in slapd.conf (to checkpoint after 1024kb or 5 minutes,
90 for example), this does not checkpoint every 5 minutes as you may think.
91 The explanation from Howard is:
93 'In OpenLDAP 2.1 and 2.2 the checkpoint directive acts as follows - *when there
94 is a write operation*, and more than <check> minutes have occurred since the
95 last checkpoint, perform the checkpoint. If more than <check> minutes pass after
96 a write without any other write operations occurring, no checkpoint is performed,
97 so it's possible to lose the last write that occurred.''
99 In other words, a write operation occurring less than "check" minutes after the
100 last checkpoint will not be checkpointed until the next write occurs after "check"
101 minutes have passed since the checkpoint.
103 This has been modified in 2.3 to indeed checkpoint every so often; in the meantime
104 a workaround is to invoke "db_checkpoint" from a cron script every so often, say 5 minutes.
108 Exporting to a new system......