Re: Calculate the size of the resident portion of ONLINE

In article <32ABDC7C.5341@mch.sni.de>, "Markus G. Holzbauer" <markus.holzbauer@mch.sni.de> writes >The formula on page 2-22 (INFORMIX-Online Dynamic >Server Performance Guide V7.2) is not correct. >f.e.: >BUFFERS=4000, LOCKS=10000, PHYSBUF=64, LOGBUFF=64 >With the formula the resident size shoud be >13986880 Bytes, onstat -g seg says: 16539648 Bytes >--> difference over 2 MBytes ! > >Anybody knows why ? The resident portion also contains some other tables:- Shared memory header - defines where the other tables are (usually ~1K - size not configurable, depends upon the platform) Hashs tables - Three tables used to speed up access to the lock table, active tblspace table and buffer table. Chunk table - Used to locate chunks on disk. Also a mirror chunk table if Online mirroring is used. Dbspace table - One entry per dbspace/blobspace. Page cleaner table - Defines state and location of page cleaner threads. Tblspace table - Used to track active tblspaces. Transaction table - Used to track transactions. User table - One entry per user thread. Usually these form a very small percentage of resident memory compared to the buffers (which are either 2/4K each or locks (there usually are thousands of locks defined). I have not sent the Online Performance Guide (I went on the training couse instead, but I would imagine that the calculation is meant to be give you an estimate rather than an exact value. Most Online 7 systems use >100Mb of memory so 2Mb is only 2% - close enough. -- David Williams