| From: | Anthony Iliopoulos <ailiop(at)altatus(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Greg Stark <stark(at)mit(dot)edu>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Geoff Winkless <pgsqladmin(at)geoff(dot)dj>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Bruce Momjian <bruce(at)momjian(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Catalin Iacob <iacobcatalin(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: PostgreSQL's handling of fsync() errors is unsafe and risks data loss at least on XFS |
| Date: | 2018-04-09 19:44:31 |
| Message-ID: | 20180409194431.GD18969@technoir |
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| Lists: | pgsql-hackers |
On Mon, Apr 09, 2018 at 12:29:16PM -0700, Andres Freund wrote:
> On 2018-04-09 21:26:21 +0200, Anthony Iliopoulos wrote:
> > What about having buffered IO with implied fsync() atomicity via
> > O_SYNC?
>
> You're kidding, right? We could also just add sleep(30)'s all over the
> tree, and hope that that'll solve the problem. There's a reason we
> don't permanently fsync everything. Namely that it'll be way too slow.
I am assuming you can apply the same principle of selectively using O_SYNC
at times and places that you'd currently actually call fsync().
Also assuming that you'd want to have a backwards-compatible solution for
all those kernels that don't keep the pages around, irrespective of future
fixes. Short of loading a kernel module and dealing with the problem directly,
the only other available options seem to be either O_SYNC, O_DIRECT or ignoring
the issue.
Best regards,
Anthony
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