On 07/12/2010 07:40 PM, Quanah Gibson-Mount wrote:
--On Monday, July 12, 2010 5:01 PM +0200 [email protected] wrote:
Attached to this message you'll find a quick and dirty bash script that
should determine the cachesize for an in-production bdb/hdb backend by
taking dn2id and id2entry as well as all existing indexes into account.
Internally the script calls the db_stat tool in combination with the
formulas found in the 2.4 admin guide under:
http://www.openldap.org/doc/admin24/tuning.html#Caching
Are you trying to determine the size of the cache in use, or what the
size of the cache should be? If it is the latter, you just use the du
-c -h output of *.bdb. If it is the former, it sounds like your script
isn't calculating the right data.
Ahh I see - thanks! It seems that we do not need to calculate the
cachesize (see below). Nevertheless, as I'm using cn=config I'm a little
bit confused regarding the available different cache settings: The
related cn=config configuration directives are all prefixed by
"olcDb..." where olcDbCachesize for example seems to store the related
DB_CONFIG setting but olcDbDnCachesize seems to be focused on slapd
internal use.
BTW: slapd.conf's "dbconfig" directive ("convenience settings" mentioned
in man slapd-bdb.5) are not transformed into cn=config format when using
slaptest -f -F (I'm using slapd 2.4.21). slapd.conf's dbconfig directive
seems to be ignored during slaptest -f -F.
Last but not least please let me summarize my current understanding
after reading AdminGuide2.4 once again:
Section 21.4.1. ==> Berkeley DB Cache
21.4.1.(a) ==> slapadd import cachesize
Cachesize is the overall filesize of *.bdb
21.4.1.(b) ==> operation cachesize
Cachesize is the filesize of id2entry.bdb + 10%
BDB Cachesize is configureable various ways:
- slapd.conf: (dbconfig ...)
- cn=config: (olcDbCacheSize: x)
- DB_CONFIG: (set_cachesize 0 x 1)
DB_CONFIG (if exists) takes precedence
Section 21.4.1.1. ==> Calculating Cachesize
only needed in case the above file sizes do not completely fit
into available free memory. As we've currently enough free RAM
we can skip these calculations.
Section 21.4.2. ==> slapd(8) Entry Cache (cachesize)
cn=config (olcDbDNcacheSize: y)
Section 21.4.3. ==> IDL Cache (idlcachesize)
cn=config (olcDbIDLcacheSize: z)
recommendation: z=y (for bdb)
recommendation: z=3x y (for hdb)
