Re: Something else about Redo Logs disappearing - Mailing list pgsql-general

From Tom Lane
Subject Re: Something else about Redo Logs disappearing
Date
Msg-id 2191826.1591680440@sss.pgh.pa.us
Whole thread Raw
In response to Re: Something else about Redo Logs disappearing  (Adrian Klaver <adrian.klaver@aklaver.com>)
Responses Re: Something else about Redo Logs disappearing  (Peter <pmc@citylink.dinoex.sub.org>)
List pgsql-general
Adrian Klaver <adrian.klaver@aklaver.com> writes:
> On 6/8/20 7:33 PM, Peter wrote:
>> That "cp" is usually not synchronous. So there is the possibility
>> that this command terminates successfully, and reports exitcode zero
>> back to the Postgres, and then the Postgres will consider that log
>> being safely away.

> Which is why just following the above command in the docs is:
> "(This is an example, not a recommendation, and might not work on all 
> platforms.) "

Yeah.  There have been discussions about changing that disclaimer to be
more forceful, because in point of fact a plain "cp" is generally not safe
enough.  You need to fsync the written file, and on many filesystems you
also have to fsync the directory it's in.

> Generally for peace of mind folks use third party tools like:

+1.  Rolling your own archive script is seldom advisable.

            regards, tom lane



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