Re: pg_basebackup, pg_receivexlog and data durability (was: silent data loss with ext4 / all current versions)

On 5/13/16 2:39 AM, Michael Paquier wrote:
> So, attached are two patches that apply on HEAD to address the problem
> of pg_basebackup that does not sync the data it writes. As
> pg_basebackup cannot use directly initdb -S because, as a client-side
> utility, it may be installed while initdb is not (see Fedora and
> RHEL), I have refactored the code so as the routines in initdb.c doing
> the fsync of PGDATA and other fsync stuff are in src/fe_utils/, and
> this is 0001.

Why fe_utils?  initdb is not a front-end program.

> Patch 0002 is a set of fixes for pg_basebackup:
> - In plain mode, fsync_pgdata is used so as all the tablespaces are
> fsync'd at once. This takes care as well of the case where pg_xlog is
> a symlink.
> - In tar mode (no stdout), each tar file is synced individually, and
> the base directory is synced once at the end.
> In both cases, failures are not considered fatal.

Maybe there should be --nosync options like initdb has?

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services