| From: | Christophe Pettus <xof(at)thebuild(dot)com> |
|---|---|
| To: | Greg Stark <stark(at)mit(dot)edu> |
| Cc: | 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>, 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: | 2018-04-08 21:28:43 |
| Message-ID: | 67F91A87-A7AA-4062-803F-8D2086DAB5A0@thebuild.com |
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| Lists: | pgsql-hackers |
> On Apr 8, 2018, at 14:23, Greg Stark <stark(at)mit(dot)edu> wrote:
>
> They consider dirty filesystem buffers when there's
> hardware failure preventing them from being written "a memory leak".
That's not an irrational position. File system buffers are *not* dedicated memory for file system caching; they're being used for that because no one has a better use for them at that moment. If an inability to flush them to disk meant that they suddenly became pinned memory, a large copy operation to a yanked USB drive could result in the system having no more allocatable memory. I guess in theory that they could swap them, but swapping out a file system buffer in hopes that sometime in the future it could be properly written doesn't seem very architecturally sound to me.
--
-- Christophe Pettus
xof(at)thebuild(dot)com
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