Re: hanging for 30sec when checkpointing - Mailing list pgsql-admin

From Tom Lane
Subject Re: hanging for 30sec when checkpointing
Date
Msg-id 20457.1076375779@sss.pgh.pa.us
Whole thread Raw
In response to Re: hanging for 30sec when checkpointing  ("scott.marlowe" <scott.marlowe@ihs.com>)
Responses Re: hanging for 30sec when checkpointing  ("scott.marlowe" <scott.marlowe@ihs.com>)
List pgsql-admin
"scott.marlowe" <scott.marlowe@ihs.com> writes:
> That said we have a really HUGE (~200 drive) IDE storage array my web /
> app server sits on top of.  No clue if that thing will reliably work under
> a database, and I'm in no hurry to find out.

> But since the fsync on WAL is all that seems important, I could always
> initlocation a big chunk of it and keep the WAL local and I should be ok.

Unfortunately not --- at checkpoint time, the constraint goes the other
way.  We have to be sure all the data file updates are down to disk
before we write a checkpoint record to the WAL log.  So you can still
get screwed if the data-file drive lies about write completion.

            regards, tom lane

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