Setting DB_TXN_NOSYN in DB_CONFIG when loading your database is a good thing to do to speed up performance, this is because writes will not be flushed or logs written on transaction commit. If you *leave this setting set* and your application fails, or you loose power on your system, it is possible some number of the most recently committed transactions may be undone during recovery. The number of transactions at risk is governed by how many log updates can fit into the log buffer, how often the operating system flushes dirty buffers to disk, and how often the log is checkpointed. Even worse, if there is database or transaction log file loss or corruption (for example, if a disk drive fails), then catastrophic recovery (read: from backups) is necessary, and Berkeley DB recovery will only be able to restore the system to the state of the last archived log file. In this case, information may also have been lost.
After your data has been loaded, DB_TXN_NOSYN should *be removed* from DB_CONFIG and slapd restarted. Although many parameters in DB_CONFIG (such as cachesize) can only be set once as they apply to the creation of the database environment and to change them you need to destroy and recreate it, the DB_TXN_NOSYNC flag can be changed between runs. Setting DB_TXN_NOSYNC should *only* be done to increase performance at the cost of sacrificing transactional durability, except in replicated environments (see http://www.sleepycat.com/docs/ref/rep/trans.html). What many people do (if you search the openldap mailing list you will confirm this), is to set the following in the DB_CONFIG: # Just use these settings when doing slapadd, comment them out # and reload slapd afterwards, or risk data loss #set_flags DB_TXN_NOSYNC #set_flags DB_TXN_NOT_DURABLE this way they are commented out, and there is a warning. When you go and do your slapadd you uncomment them, fire things up and then slapadd. When you are done you comment them out and reload slapd. You *can* leave these enabled, but you are risking data loss. See for reference: http://www.openldap.org/faq/index.cgi?_highlightWords=db_txn_nosync&file=1072 http://www.openldap.org/faq/index.cgi?_highlightWords=db_txn_nosync&file=893 It is also highly recommended that you tune your BDB environment according to your needs or you will experience slowdown, see the following: http://www.stanford.edu/services/directory/openldap/configuration/bdb-config-42.html http://www.openldap.org/faq/data/cache/1075.html Micah
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