Windl, Ulrich wrote: > Hi again! > > I've implemented a Nagios compatible monitor for the MDB freespace, but I'm > trying to understand: > The "unused pages" are non-fragmented, obviously > The "free pages" may be scattered all over, but are completely free > May there exist partially free pages that are not accounted in the monitor > info?
No. There is no such thing as a partially free page. > Also for a huge change request are contiguous pages needed, or is only the > number of available pages important? > > Does MDB care about fragmentation at all? LMDB is a key/value store, large values are stored on contiguous pages. Fragmentation will affect the search for contiguous pages for large values. back-mdb may change multiple underlying records for a given LDAP modification. Indices are small, and unaffected by fragmentation. Other things may have varying sizes. > > Kind regards, > Ulrich Windl > >> -----Original Message----- >> From: Howard Chu <h...@symas.com> >> Sent: Friday, April 25, 2025 6:16 PM >> To: Windl, Ulrich <u.wi...@ukr.de>; openldap-technical@openldap.org >> Subject: [EXT] Re: MDB monitoring: How many free pages actually? >> >> Windl, Ulrich wrote: >>> Hi, >>> >>> >>> >>> Considering this monitoring information, I wonder: >>> >>> olmMDBPagesMax: 12800 >>> olmMDBPagesUsed: 9229 >>> olmMDBPagesFree: 3810 >> >>> Is the number of actual free pages 12800 - 9229 + 3810, i.e. "unallocated >> (12800 - 9229)" plus "usable" (3810)? >> >> Yes. "Pages Free" are used pages that are reusable. >> >>> How many free pages are needed before updates stop working? >> >> That depends on the size of an update. >> >> >> -- >> -- Howard Chu >> CTO, Symas Corp. http://www.symas.com >> Director, Highland Sun http://highlandsun.com/hyc/ >> Chief Architect, OpenLDAP http://www.openldap.org/project/ > -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
