RE: Informix 7.1 on Digital UNIX - raw or cooked?

In article <memo.19980915200320.18397F@wfsoftware.compulink.co.uk>, paulw@wfsoftware.co.uk wrote: > In article <6tkbit$7gh$1@news.xmission.com>, > David.Ashby@workcover.nsw.gov.au (Ashby, David) wrote: > > > > > > > The decision to go raw or cooked should not just be based on > > performance. A more important consideration in my opinion is > > recoverability. With a cooked file system IO's are fed to the OS for > > writing, in a worst case scenario the following could happen: > > - the server crashes > > - Informix believes that a buffer has been written to disk > > - but the OS has cached it and it has not been written > > - when Informix is brought back online it does not recover the > > suspect page > > > > If you can use KIO with raw chunks I believe that the OS cache is not > > used. > [cutting] > > I accept the above but I read the question as to whether to use raw disk > or Digital OS because its rumoured to be quick. > > Paul Watson # I don't suffer from > WF Software Ltd. # stress, I'm just > Tel. (+44) 1436 674729 # a carrier > Fax. (+44) 1436 678693 # > www.wfsoftware.co.uk > Good point, Paul. I believe that Informix introduced the option of using raw with the Informix Turbo product, back when. At that time the UNIX file system (a part of the UNIX OS) was not as efficient and durable as it is today. Therefore "replacing" the UNIX file system with one's own method of handling data on disk, which is in a sense what using raw allows, was more efficient and had better recovery. In fact this method has been used in UNIX database design before the comercial RDBSs turned to raw. So, "choosing raw over cooked" has a lot to do with the efficiency and nature of the UNIX file system available. Today the most efficient file systems are probably written by either Veratas or Programmed Logic Corporation. Not all UNIX publishers use file systems enhanced by either of these vendors. The ideal situation would be to have a UNIX file system type designed specifically for the a relational database (UNIX supports concurrent, heterogeneous file system types) since it would very efficient and it would be _managed_ by the OS, i.e. there would be _very_ little administration or tuning needed (from the DBA). Currently the mantra of "use raw over cooked" is for the most part good advice. However, if Informix SE (which uses only cooked files) is adaquate for the job, it's a lot cheaper and easier to use than ODS. Vic Glass (a/k/a icc) -----== Posted via Deja News, The Leader in Internet Discussion ==----- http://www.dejanews.com/rg_mkgrp.xp Create Your Own Free Member Forum