Subject: Re: RAW access to files
To: None <>
From: None <>
List: tech-kern
Date: 12/11/2001 09:24:24

>> As an interresting side point, I've heard rumors that Solaris 9 will
>> include a "direct I/O" feature in UFS.  For what [good] reasons, I'm
>> not sure, but I'm sure there have to be valid reasons...
> It's been in Solaris since at least 2.6. mount -o forcedirectio does
> the trick. You can also tune it on filebasis via the stickybit, just
> chmod +t your files and they will bypass the buffercache. That's a
> common trick to do when tuning database systems.

I knew about the sticky bit, but not about forcedirectio.  Upon me
performing an RTFM op, the beta docs do quote:

'The performance of direct I/O, which is used by database applications to
access unbuffered file-system data, has been improved by allowing
concurrent read and write access to regular UFS files. Previously, an
operation that updated file data would lock out all other read or write
accesses until the update operation was completed.'

So, I guess it's not new, just improved.  Sorry for the mis-info...

"The only thing that's worse is when some guy with an iron cross tatoo
kicks the shit out of you to amuse your girlfriend.  God, I hate LA."
   - Thor Lancelot Simon