Обсуждение: AW: Allowing WAL fsync to be done via O_SYNC

> Okay ... we can fall back to O_FSYNC if we don't see either of the
> others.  No problem.  Any other weird cases out there?  I think Andreas
> might've muttered something about AIX but I'm not sure now.

You can safely use O_DSYNC on AIX, the only special on AIX is,
that it does not make a speed difference to O_SYNC. This is imho
because the jfs only needs one sync write to the jfs journal for meta info 
in eighter case (so that nobody misunderstands: both perform excellent).

Andreas

> > Okay ... we can fall back to O_FSYNC if we don't see either of the
> > others.  No problem.  Any other weird cases out there?  I think Andreas
> > might've muttered something about AIX but I'm not sure now.
> You can safely use O_DSYNC on AIX, the only special on AIX is,
> that it does not make a speed difference to O_SYNC. This is imho
> because the jfs only needs one sync write to the jfs journal for meta info
> in eighter case (so that nobody misunderstands: both perform excellent).

Hmm. Does everyone run jfs on AIX, or are there other file systems
available? The same issue should be raised for Linux (at least): have we
tried test cases with both journaling and non-journaling file systems?
Perhaps the flag choice would be markedly different for the different
options?
                    - Thomas

My UnixWare box runs Veritas' VXFS, and has Online-Data Manager 
installed. Documentation is available at http://www.lerctr.org:457/ 

There are MULTIPLE sync modes, and there are also hints an app can give 
to the FS. 

More info is available if you want. 

LER

-- 
Larry Rosenman                                                                    http://www.lerctr.org/~ler/
Phone: +1 972 414 9812                                                            E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749 US
>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 3/16/01, 9:11:51 AM, Thomas Lockhart <lockhart@alumni.caltech.edu> wrote 
regarding [HACKERS] Re: AW: Allowing WAL fsync to be done via O_SYNC:


> > > Okay ... we can fall back to O_FSYNC if we don't see either of the
> > > others.  No problem.  Any other weird cases out there?  I think Andreas
> > > might've muttered something about AIX but I'm not sure now.
> > You can safely use O_DSYNC on AIX, the only special on AIX is,
> > that it does not make a speed difference to O_SYNC. This is imho
> > because the jfs only needs one sync write to the jfs journal for meta 
info
> > in eighter case (so that nobody misunderstands: both perform excellent).

> Hmm. Does everyone run jfs on AIX, or are there other file systems
> available? The same issue should be raised for Linux (at least): have we
> tried test cases with both journaling and non-journaling file systems?
> Perhaps the flag choice would be markedly different for the different
> options?

>                      - Thomas

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Thomas Lockhart <lockhart@alumni.caltech.edu> writes:
> tried test cases with both journaling and non-journaling file systems?
> Perhaps the flag choice would be markedly different for the different
> options?

Good point.  Another reason we don't have enough data to nail this down
yet.  Anyway, the code is in there and people can run test cases if they
please...
        regards, tom lane