Re: Write cache

On Tue, 27 Jan 2004, Larry Rosenman wrote:

> Date: Tue, 27 Jan 2004 16:02:40 -0600
> From: Larry Rosenman <ler(at)lerctr(dot)org>
> To: ohp(at)pyrenet(dot)fr
> Cc: pgsql-hackers list <pgsql-hackers(at)postgresql(dot)org>
> Subject: Re: Write cache
>
>
>
> --On Tuesday, January 27, 2004 23:01:45 +0100 ohp(at)pyrenet(dot)fr wrote:
>
> > On Tue, 27 Jan 2004, Larry Rosenman wrote:
> >
> >> Date: Tue, 27 Jan 2004 15:55:49 -0600
> >> From: Larry Rosenman <ler(at)lerctr(dot)org>
> >> To: ohp(at)pyrenet(dot)fr
> >> Cc: pgsql-hackers list <pgsql-hackers(at)postgresql(dot)org>
> >> Subject: Re: Write cache
> >>
> >>
> >>
> >> --On Tuesday, January 27, 2004 22:48:42 +0100 ohp(at)pyrenet(dot)fr wrote:
> >>
> >> > On Tue, 27 Jan 2004, Larry Rosenman wrote:
> >> >
> >> >> Date: Tue, 27 Jan 2004 15:45:20 -0600
> >> >> From: Larry Rosenman <ler(at)lerctr(dot)org>
> >> >> To: ohp(at)pyrenet(dot)fr
> >> >> Cc: pgsql-hackers list <pgsql-hackers(at)postgresql(dot)org>
> >> >> Subject: Re: Write cache
> >> >>
> >> >>
> >> >>
> >> >> --On Tuesday, January 27, 2004 22:43:34 +0100 ohp(at)pyrenet(dot)fr wrote:
> >> >>
> >> >> > On Tue, 27 Jan 2004, Larry Rosenman wrote:
> >> >> >
> >> >> >> Date: Tue, 27 Jan 2004 15:38:30 -0600
> >> >> >> From: Larry Rosenman <ler(at)lerctr(dot)org>
> >> >> >> To: ohp(at)pyrenet(dot)fr, pgsql-hackers list
> >> >> >> <pgsql-hackers(at)postgresql(dot)org> Subject: Re: Write cache
> >> >> >>
> >> >> >> IDE or SCSI?
> >> >> > SCSI
> >> >> >>
> >> >> >> Why do you think the WC is screwing you?
> >> >> >>
> >> >> > Because after a sys crash, the most used filesystems (databases) are
> >> >> > screwed
> >> >> what VxFS mount options are you using?
> >> > Nothing special... And any option I could use would'nt change a thing:
> >> > the cache is on the disk itself... I did'nt look physicaly yet but
> >> > according to the docs there's no way to disable it lik I always did on
> >> > IBM...
> >> >
> >> > I was forced to buy those disk (more expensive, not better)
> >> define not special?
> >>
> >> ISTM that the driver should force it out to the disk, unless the disk is
> >> lying to the driver, or the driver is buggy.
> > That's exactly what I think: the DISK has a write cache so it's lying to
> > the controler saying data is written when it's only in the disk cache.
> >
> > That also would explain the fantastic write performance I have compared to
> > read...
> SO, I consider these disks buggy or not acceptable for use.
So do I... I have 6 disks... 250$ each...
>
> LER
>
> >>
> >>
> >> > >
> >> >>
> >> >> >> Which driver(s)?
> >> >> >>
> >> >> > Guess... ADPU320
> >> >> Hrm.
> >> >>
> >> >> >> LER
> >> >> >>
> >> >> >>
> >> >> >> --On Tuesday, January 27, 2004 22:34:46 +0100 ohp(at)pyrenet(dot)fr wrote:
> >> >> >>
> >> >> >> > Because I've lost a lot of data using postgresql (and I know for
> >> >> >> > sure this should'nt happen) I've gone a bit further reading
> >> >> >> > documentations on my disks and...
> >> >> >> >
> >> >> >> > I have FUJITSU MAP3367NC 36G 10000 rpm disks, those disk have a
> >> >> >> > write cache of 8Mb, if someone could tell me hox to turn it
> >> >> >> > off... Could'nt find it in the docs and this could very well
> >> >> >> > explain why a busy database crashes every time
> >> >> >> >
> >> >> >> > Thanks for your help
> >> >> >> >
> >> >> >> > --
> >> >> >> > Olivier PRENANT Tel: +33-5-61-50-97-00 (Work)
> >> >> >> > 6, Chemin d'Harraud Turrou +33-5-61-50-97-01 (Fax)
> >> >> >> > 31190 AUTERIVE +33-6-07-63-80-64 (GSM)
> >> >> >> > FRANCE Email: ohp(at)pyrenet(dot)fr
> >> >> >> > ----------------------------------------------------------------
> >> >> >> > --- --- --- ----- Make your life a dream, make your dream a
> >> >> >> > reality. (St Exupery)
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >
> >> >> > --
> >> >> > Olivier PRENANT Tel: +33-5-61-50-97-00 (Work)
> >> >> > 6, Chemin d'Harraud Turrou +33-5-61-50-97-01 (Fax)
> >> >> > 31190 AUTERIVE +33-6-07-63-80-64 (GSM)
> >> >> > FRANCE Email: ohp(at)pyrenet(dot)fr
> >> >> > -------------------------------------------------------------------
> >> >> > --- --- ----- Make your life a dream, make your dream a reality. (St
> >> >> > Exupery)
> >> >>
> >> >>
> >> >>
> >> >>
> >> >
> >> > --
> >> > Olivier PRENANT Tel: +33-5-61-50-97-00 (Work)
> >> > 6, Chemin d'Harraud Turrou +33-5-61-50-97-01 (Fax)
> >> > 31190 AUTERIVE +33-6-07-63-80-64 (GSM)
> >> > FRANCE Email: ohp(at)pyrenet(dot)fr
> >> > ----------------------------------------------------------------------
> >> > --- ----- Make your life a dream, make your dream a reality. (St
> >> > Exupery)
> >>
> >>
> >>
> >>
> >
> > --
> > Olivier PRENANT Tel: +33-5-61-50-97-00 (Work)
> > 6, Chemin d'Harraud Turrou +33-5-61-50-97-01 (Fax)
> > 31190 AUTERIVE +33-6-07-63-80-64 (GSM)
> > FRANCE Email: ohp(at)pyrenet(dot)fr
> > -------------------------------------------------------------------------
> > ----- Make your life a dream, make your dream a reality. (St Exupery)
>
>
>
>

--
Olivier PRENANT Tel: +33-5-61-50-97-00 (Work)
6, Chemin d'Harraud Turrou +33-5-61-50-97-01 (Fax)
31190 AUTERIVE +33-6-07-63-80-64 (GSM)
FRANCE Email: ohp(at)pyrenet(dot)fr
------------------------------------------------------------------------------
Make your life a dream, make your dream a reality. (St Exupery)