Re: ext3 journalling type

Dawid Kuroczko wrote:
> The ext3fs allows to selet type of journalling to be used with
> filesystem. Journalling pretty much "mirrors" the work of WAL
> logging by PostgreSQL... I wonder which type of journalling
> is best for PgSQL in terms of performance.
> Choices include:
> journal
> All data is committed into the journal prior to being
> written into the main file system.
> ordered
> This is the default mode. All data is forced directly
> out to the main file system prior to its metadata being
> committed to the journal.
> writeback
> Data ordering is not preserved - data may be written into
> the main file system after its metadata has been commit-
> ted to the journal. This is rumoured to be the highest-
> throughput option. It guarantees internal file system
> integrity, however it can allow old data to appear in
> files after a crash and journal recovery.
>
> Am I right to assume that "writeback" is both fastest and at the same
> time as safe to use as ordered? Maybe any of you did some benchmarks?

Yes. I have seen benchmarks that say writeback is fastest but I don't
have any numbers handy.

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