Re: AIO vp...

Stefan Weideneder wrote: > > Art S. Kagel wrote: > > > > SUNIL S. SINGH wrote: > > > > > > Hi all !!! > > > > > > I have a little doubt here abt AIO vp. > > > One of the informix manual says tht IDS uses kernel AIO (kio) I/o method, > > > ie performing I/O through operating system, if chunk is UNIX raw device > > > and it relies on AIO vp for performing I/O directly if chunk is UNIX > > > cooked file. > > > > > > How far is it correct ?? > > > I think it is other way round. > > > > No that is correct. By default, on most platforms, RAW device chunks > > are handled by KAIO threads and COOKED device/file chunks are handled > > by AIO VPs. > > > > Art S. Kagel > > ... on most platforms, except some platforms, i.e. HP-UX. Well let's be clear, Stefan. Both our posts leave the question of exactly what is platform dependent open. The dependency is whether KAIO is enabled or disabled by default. If KAIO is enabled, either implicitely (because it is the default and the KAIOOFF environment var is not defined) or explicitely (because the KAIOON environment var is defined where KAIO is not the default), then KAIO handles RAW chunks and AIO VPs handle COOKED chunks. If KAIO is not enabled, either because it is not implemented for your platform, it has been disabled, or it has not been enabled (depending on the platform default), then AIO VPs handle all I/O. There that's better. Sorry to have been muddy. Art S. Kagel