maria-discuss team mailing list archive

[Cédric Counotte <cedric.counotte@xxxxxxxxxx>]

You mean the ib_logfile0, right? It's 1GB yes, but not sure why or what it helps (or not) with.

Isn't that log used in case of crash only?

Cause replication is using mysql-bin.* log files which I have also set to 1GB and got 144 of them per day, and keeping one day, just in case the replication fails for so long (I've seen it stops very often but that's another problem).


Now considering that:
	>>> If it leaves the log to fill up to 90% and the state transfer hits, it could be that with the checkpoint age already high, there just isn't enough headroom to avoid a massive stall. Purely guessing here without any telemetry.
and
	>>>SET GLOBAL innodb_max_dirty_pages_pct_lwm=0.001;

And the fact that I have 1GB log file, and 1GB bin log files as well, could that be the problem?

If so, would that mean that setting either innodb_max_dirty_pages_pct_lwm or changing the log (or binlog) file size could fix that issue?



-----Message d'origine-----
De : Gordan Bobic <gordan.bobic@xxxxxxxxx> 
Envoyé : mercredi 27 juillet 2022 15:23
À : jocelyn fournier <jocelyn.fournier@xxxxxxxxx>
Cc : Cédric Counotte <cedric.counotte@xxxxxxxxxx>; Marko Mäkelä <marko.makela@xxxxxxxxxxx>; Mailing-List mariadb <maria-discuss@xxxxxxxxxxxxxxxxxxx>; Pierre LAFON <pierre.lafon@xxxxxxxxxx>
Objet : Re: [Maria-discuss] MariaDB server horribly slow on start

10.5+ only uses a single log file, so that is 1x1GB.
And 1GB is tiny, IMO it should be a default these days.
I would only even consider something smaller if I was running on an older Raspberry Pi or something similarly constrained.


On Wed, Jul 27, 2022 at 4:11 PM jocelyn fournier <jocelyn.fournier@xxxxxxxxx> wrote:
>
> Hi Cédric!
>
> Just to be sure, do you really need the 2x 1G log_file_size ?
>
> BR,
>   Jocelyn Fournier
>
> > Le 27 juil. 2022 à 14:36, Cédric Counotte <cedric.counotte@xxxxxxxxxx> a écrit :
> >
> > Reading this: https://jira.mariadb.org/browse/MDEV-27295
> >
> > It's quite unclear when it is fixed or reverted.
> >
> > That said I read that the following setting might fix it:
> >       SET GLOBAL innodb_max_dirty_pages_pct_lwm=0.001;
> >
> > Is that correct and should I try that and see if that helps?
> >
> >
> > -----Message d'origine-----
> > De : Gordan Bobic <gordan.bobic@xxxxxxxxx> Envoyé : mercredi 27 
> > juillet 2022 14:29 À : Marko Mäkelä <marko.makela@xxxxxxxxxxx> Cc : 
> > Cédric Counotte <cedric.counotte@xxxxxxxxxx>; Mailing-List mariadb 
> > <maria-discuss@xxxxxxxxxxxxxxxxxxx>
> > Objet : Re: [Maria-discuss] MariaDB server horribly slow on start
> >
> > On Wed, Jul 27, 2022 at 3:08 PM Marko Mäkelä <marko.makela@xxxxxxxxxxx> wrote:
> >>
> >> On Wed, Jul 27, 2022 at 2:48 PM Gordan Bobic <gordan.bobic@xxxxxxxxx> wrote:
> >>>
> >>> There is no supported downgrade path other than logical dump+restore.
> >>> There are also no packages built for distros where the major version is older than what ships with the distro.
> >>>
> >>> Since your queries seem to end up stuck in commit stage, it could be related to redo log flushing, which behaves very erratically on 10.5+. If it leaves the log to fill up to 90% and the state transfer hits, it could be that with the checkpoint age already high, there just isn't enough headroom to avoid a massive stall. Purely guessing here without any telemetry.
> >>
> >> I think that you may refer to InnoDB page flushing. There was some 
> >> misunderstanding around that, and indeed some partly unintended or 
> >> uninformed changes in behaviour (in 10.5.7 and 10.5.8) that were 
> >> reverted later. It could be useful to read 
> >> https://jira.mariadb.org/browse/MDEV-27295.
> >
> > What version was it reverted in?
> > I am still seeing the errant redo log flushing behaviour in 10.5.15.
> > It looks like no flushing happens until the hwm is reached at about 
> > 85% full. It then tries to commit everything down to the lwm. And 
> > inbetween it doesn't do anything, even while everything is idle and 
> > it should be running down the 
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