Re: [HACKERS] Performance while loading data and indexing

Greg Copeland wrote:
> > The paper does recommend ext3, but the differences between file systems
> > are very small. If you are seeing 'cp' as slow, I wonder if it may be
> > something more general, like poorly tuned hardware or something. You can
> > use 'dd' to throw some data around the file system and see if that is
> > showing slowness; compare those numbers to another machine that has
> > different hardware/OS.
> >
> > Also, though ext3 is slower, turning fsync off should make ext3 function
> > similar to ext2. That would be an interesting test if you suspect ext3.
>
> I'm curious as to why you recommended ext3 versus some other (JFS,
> XFS). Do you have tests which validate that recommendation or was it a
> simple matter of getting the warm fuzzies from familiarity?

I used the attached email as a reference. I just changed the wording to
be:

File system choice is particularly difficult on Linux because there are
so many file system choices, and none of them are optimal: ext2 is not
entirely crash-safe, ext3 and xfs are journal-based, and Reiser is
optimized for small files. Fortunately, the journaling file systems
aren't significantly slower than ext2 so they are probably the best
choice.

so I don't specifically recommend ext3 anymore. As I remember, ext3 is
good only in that it can read ext2 file systems. I think XFS may be the
best bet.

Can anyone clarify if "data=writeback" is safe for PostgreSQL.
Specifically, are the data files recovered properly or is this option
only for a filesystem containing WAL?

--
Bruce Momjian | http://candle.pha.pa.us
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