Re: Calculate the size of the resident portion of ONLINE

David Williams wrote: > > 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 ! > > Ok, with BUFFERS=8000, LOCKS=20000, ... the difference is only 1 MByte ! > >Anybody knows why ? Phi is 3.1415... not 3. > > 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) 1 or 2 kbyte is not the problem > 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. How many chunks ? 200, 1000 ? Versions >= 7.10.UD1 don't have the Parameter CHUNKS. > Dbspace table - One entry per dbspace/blobspace. How many Dbsapces ? 200, 1000 ? Versions >= 7.10.UD1 don't have the Parameter DBSPACES > Page cleaner table - Defines state and location of page cleaner > threads. Resident Size CLEANERS=1 == Resident Size CLEANERS=128 > Tblspace table - Used to track active tblspaces. How many Tblspacess ? 200, 1000 ? Versions >= 7.10.UD1 don't have the Parameter TBLSPACES > Transaction table - Used to track transactions. How many Transactions ? 200, 1000 ? Versions >= 7.10.UD1 don't have the Parameter TRANSACTIONS > User table - One entry per user thread. How many Users ? 200, 1000 ? Versions >= 7.10.UD1 don't have the Parameter USERTHREADS > > 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. 2 MByte from 16 MByte = 12,5 % ! > > -- > David Williams -- With best regards Markus Holzbauer markus.holzbauer@mch.sni.de Online or not Online, that's the question here !?