Re: PostgreSQL's handling of fsync() errors is unsafe and risks data loss at least on XFS

Hi,

On 2018-04-09 13:25:54 -0700, Mark Dilger wrote:
> I was reading this thread up until now as meaning that the standby could
> receive corrupt WAL data and become corrupted.

I don't see that as a real problem here. For one the problematic
scenarios shouldn't readily apply, for another WAL is checksummed.

There's the problem that a new basebackup would potentially become
corrupted however. And similarly pg_rewind.

Note that I'm not saying that we and/or linux shouldn't change
anything. Just that the apocalypse isn't here.


> Your comment reads as if this is a problem isolated to whichever server has
> the problem, and will not get propagated to other servers.  Am I reading
> that right?

I think that's basically right. There's cases where corruption could get
propagated, but they're not straightforward.

Greetings,

Andres Freund