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Re: MariaDB server horribly slow on start


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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