Re: Something else about Redo Logs disappearing

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