Re: Filesystem Direct I/O and WAL sync option

Поиск
Список
Период
Сортировка
От Gregory Stark
Тема Re: Filesystem Direct I/O and WAL sync option
Дата
Msg-id 87lkdx0y5d.fsf@oxford.xeocode.com
обсуждение исходный текст
Ответ на Re: Filesystem Direct I/O and WAL sync option  (Dimitri <dimitrik.fr@gmail.com>)
Ответы Re: Filesystem Direct I/O and WAL sync option  (Dimitri <dimitrik.fr@gmail.com>)
Список pgsql-performance
"Dimitri" <dimitrik.fr@gmail.com> writes:

> Yes, disk drives are also having cache disabled or having cache on
> controllers and battery protected (in case of more  high-level
> storage) - but is it enough to expect data consistency?... (I was
> surprised about checkpoint sync, but does it always calls write()
> anyway? because in this way it should work without fsync)...

Well if everything is mounted in sync mode then I suppose you have the same
guarantee as if fsync were called after every single write. If that's true
then surely that's at least as good. I'm curious how it performs though.

Actually it seems like in that configuration fsync should be basically
zero-cost. In other words, you should be able to leave fsync=on and get the
same performance (whatever that is) and not have to worry about any risks.

--
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com


В списке pgsql-performance по дате отправления:

Предыдущее
От: Richard Huxton
Дата:
Сообщение: Re: Query is taking 5 HOURS to Complete on 8.1 version
Следующее
От: Axel Rau
Дата:
Сообщение: Re: Delete Cascade FK speed issue