Red Hat Directory Server 7.1 Performance Tuning and Sizing Guidelines

Step 2: Prime the directory by sending the following ldapsearch command (label it as ldapsearch command 1):

#./ldapsearch –b “<root suffix>” –h <host> -p <port> -D “cn=directory manager” –w passwd “objectclass=*” > /dev/null

Step 3: check db related monitoring attributes by sending a different ldapsearch request. (label it as ldapsearch command 2):

#./ldapsearch -p PORT -b "cn=monitor, cn=ldbm database, cn=plugins, cn=config" –D "cn=directory manager" -w PASSWD “objectclass=*" grep dbcache

dbcachehits: 236

dbcachetries: 280

dbcachehitratio: 84

dbcachepagein: 44

dbcachepageout: 0

dbcacheroevict: 0

dbcacherwevict: 0

•Step 4: If dbcachepageout, dbcacheroevict and dbcacherwevict are not equal to zero, you might want to increase nsslapd-dbcachesize, and repeat from Step 2 until these three attributes equal to zero or dbcachesize reaches the maximum value or dbcachepagein stops increasing. When nsslapd-dbcachesizeis not big enough, pages need to be discarded from the dbcache to make room for new pages. This is indicated by attributes dbcachepageout, dbcacheroevict and dbcacherwevict. For more information about these attributes, please refer to and “Red Hat Directory Server 7.1 Configuration, Command, and File Reference Guide”

To estimate the amount of RAM needed for an optimized database cache, you can use the following formula:

Equation 1: Estimate Size of Database Cache

dbcachesize = SUM(allDB4files)

•Please note: Equation 1 only gives you a very rough estimation for dbcachesize. When estimating database cache size, only the database (db4) files that your operations need should be included. As an example, if your directory server only needs to support exact search requests on the “cn” attribute, you may need just 354MB dbcache instead of 685MB dbcache which is the sum of all database (db4) files for the 250K databases. For more information about how to manage indexes, please refer to “Red Hat Directory Server 7.1 Administrator’s Guide”

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