| From: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Christophe Pettus <xof(at)thebuild(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Robert Haas <robertmhaas(at)gmail(dot)com>, Anthony Iliopoulos <ailiop(at)altatus(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, 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 01:35:06 |
| Message-ID: | CAMsr+YGFqgMWdfM2kOMCRyMofYe8zwsEuHZ3vc+rzSZpPty0Eg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 9 April 2018 at 06:29, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> I think the big problem is that we don't have any way of stopping
> Postgres at the time the kernel reports the errors to the kernel log, so
> we are then returning potentially incorrect results and committing
> transactions that might be wrong or lost.
Right.
Specifically, we need a way to ask the kernel at checkpoint time "was
everything written to [this set of files] flushed successfully since the
last time I asked, no matter who did the writing and no matter how the
writes were flushed?"
If the result is "no" we PANIC and redo. If the hardware/volume is screwed,
the user can fail over to a standby, do PITR, etc.
But we don't have any way to ask that reliably at present.
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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