Hello Howard, Thanks for the helpful information! All about the back-mdb sounds so good! Will the new back-mdb included in the next release? Is it recommended to use this backend in production environment?
Thanks for hard work on the great OpenLDAP! Meike 2011/11/1 Howard Chu <[email protected]>: > Meike Stone wrote: >> >> Hello, >> >> time ago, we installed a Linux Guest with OpenLDAP (db size appox. >> 650MByte / ) server in a ESXi environment. >> Maybe because of a read/write ratio 100:1, the hard discs where heavy >> used by writing bdb backends memory mapped files. >> The CPU in that Linux system had iowait (top) between 80% and 100% and >> the other VMs on the ESXi went slow down. >> >> After changing to shared memory (shm_key), all problems with disc IO where >> gone. >> >> I read in the mailing list and on "OpenLDAP performance tuning" guide, >> that it does not matter if using memory mapped files or shared memory >> until the database is over 8GB. But why we had such problems? >> >> Please note, the OpenLDAP was operating very fast with the memory >> mapped files, because of using indexes and proper caching. >> >> >> Now, I want install more than one OpenLDAP server on one Linux system >> (now real Hardware). >> Every OpenLDAP server will be bind on a separate IP and DNS host name. >> >> So in this scenario it is hard to calculate the shared memory and >> assign each LDAP server to the right shared memory region (key). >> >> Therefore I want go back to memory mapped files. Are there any >> recommendation for sizing the Linux system like: >> - type of file system (ext3, ext4, xfs, ..) >> - parameters of file system (syncing -> commit=nrsec, data=*, ... ) >> - swap using (swappiness, dirty_background_ratio) >> - ??? > > Also, back-mdb (in git master) will behave much better in a VM deployment. > (Actually, back-mdb behaves better than back-bdb/hdb in all environments.) > > -- > -- Howard Chu > CTO, Symas Corp. http://www.symas.com > Director, Highland Sun http://highlandsun.com/hyc/ > Chief Architect, OpenLDAP http://www.openldap.org/project/ >
