Re: [GENERAL] Interesting comments about fsync on Linux

[Greg Smith]

On Sat, 3 May 2008, Bruno Wolff III wrote:


The suggestion is that fsync isn't really safe on Linux as it is currently
implented.


The issue of needing to turn off underlying disk write caches under Linux 
is documented: 
http://www.postgresql.org/docs/8.3/interactive/wal-reliability.html


As for concerns about individual blocks not being written in order, as 
long as everything associated with a commit is done when the fsync returns 
that shouldn't be an issue for the PostgreSQL WAL implementation.


It is easier to shoot yourself in the foot than it should be on Linux, but 
it's possible to avoid that with care.


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* Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD

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[GENERAL] Interesting comments about fsync on Linux

[Bruno Wolff III]

I was looking for some information on how write barriers interact with
software raid and ran across the following kernel thread referenced on LWN.
The suggestion is that fsync isn't really safe on Linux as it is currently
implented. (The thread was from February 2008, so it probably still
applies.)
http://lwn.net/Articles/270891/

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