Re: Calculate the size of the resident portion of ONLINE

In article <32AE8C81.69D5@mch.sni.de>, "Markus G. Holzbauer" <markus.holzbauer@mch.sni.de> writes >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. Hoever many chunks you have open at the time - it's now dynamic. >> Dbspace table - One entry per dbspace/blobspace. >How many Dbsapces ? 200, 1000 ? Versions >= 7.10.UD1 don't have the >Parameter >DBSPACES Again it's now dynamic >> 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 Again it's now dynamic >> Transaction table - Used to track transactions. >How many Transactions ? 200, 1000 ? Versions >= 7.10.UD1 don't have the >Parameter >TRANSACTIONS Again it's now dynamic >> User table - One entry per user thread. >How many Users ? 200, 1000 ? Versions >= 7.10.UD1 don't have the >Parameter >USERTHREADS Again it's now dynamic >> >> 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 % ! Very few Online systems used only 16Mb of memory! >> >> -- >> David Williams -- David Williams