Re: Patch to improve reliability of postgresql on linux nfs

On 9 September 2011 01:04, George Barnett <gbarnett@atlassian.com> wrote:
> After looking through the code I found that when postgres calls write() it doesn't retry.  In order to address the issue with the PANIC in the WAL writer I set the sync method to o_sync which solved the issue in that part of the code, however I was still seeing failures in other areas of the code (such as the FileWrite function).  Following this, I spoke to an NFS guru who pointed out that writes under linux are not guaranteed to complete unless you open up O_SYNC or similar on the file handle.

Have you run the test with varying wal_sync_method values?  On Linux
the default is fdatasync because historically Linux hasn't supported
O_DSYNC (a wal_sync_method value of open_datasync).  But I believe as
of Kernel 2.6.33 it does support it.  Have you tried modifying this
parameter in your tests?  Are you even using Linux? (you haven't
specified)

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Thom Brown
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