Re: [RFC] What should we do for reliable WAL archiving?

On Sun, Mar 16, 2014 at 3:53 PM, MauMau <maumau307@gmail.com> wrote:
> Hello,
>
> The PostgreSQL documentation describes cp (on UNIX/Linux) or copy (on
> Windows) as an example for archive_command.  However, cp/copy does not sync
> the copied data to disk.  As a result, the completed WAL segments would be
> lost in the following sequence:
>
> 1. A WAL segment fills up.
>
> 2. The archiver process archives the just filled WAL segment using
> archive_command.  That is, cp/copy reads the WAL segment file from pg_xlog/
> and writes to the archive area.  At this point, the WAL file is not
> persisted to the archive area yet, because cp/copy doesn't sync the writes.
>
> 3. The checkpoint processing removes the WAL segment file from pg_xlog/.
>
> 4. The OS crashes.  The filled WAL segment doesn't exist anywhere any more.
>
> Considering the "reliable" image of PostgreSQL and widespread use in
> enterprise systems, I think something should be done.  Could you give me
> your opinions on the right direction?

How about using pg_receivexlog for archiving purpose?


With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com