Comments on: Dirty pages, fast shutdown, and write combining

By: Shlomi Noach

Shlomi Noach — Sat, 12 Jun 2010 03:44:33 +0000

Though it is not published yet, I have a script in openark-kit which prepares for a clean, fast shutdown; majorly by lowering the max dirty pages percent, following it until no improvement is seen for some period, then exits.
It’s a script you would run like this:
oak-prepare-shutdown && /etc/init.t/mysql stop

By: Xaprb

Xaprb — Wed, 26 May 2010 13:01:15 +0000

Dimitri, thanks for commenting. I sort of did mention that when I said “However, this is actually a useful technique for a planned fast shutdown.” I just decided to write this post without mentioning specific parameters. (I thought it would be more confusing if I had too many technical details.)

Mark R, I am not competent to answer about BPXT. How it uses memory is a good question that I need to learn more about.

By: Mark R

Mark R — Wed, 26 May 2010 12:32:42 +0000

Another possibility, is to use an engine which doesn’t work like that.

As far as I understand, PBXT does not do this at all. Instead it is crash-only and it syncs its logs at transaction commit time, so there are never ANY dirty blocks belonging to committed transactions.

This means that you can just kill -9 the process and there’s no more work. Also the shutdown is immediate as it doesn’t need to bother doing any cleanup.

By: Dimitri

Dimitri — Wed, 26 May 2010 07:28:14 +0000

Great post, Baron!
and particularly honest :-)

At the end I was surprised you did not mention the solution posted by Percona to set the dirty page percentage to zero just before a shutdown.. Any reason?..

Thank you!

Rgds,
-Dimitri