| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | Greg Smith <greg(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: We really ought to do something about O_DIRECT and data=journalled on ext4 |
| Date: | 2010-12-07 02:05:28 |
| Message-ID: | AANLkTi=nf+Mdn7bdoziVowXuMZrNPzfwb3ZncF-Q98QC@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Dec 6, 2010 at 9:04 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>
>> Mac OS X: Like Solaris, there's a similar mechanism but it's not
>> O_DIRECT; see
>> http://stackoverflow.com/questions/2299402/how-does-one-do-raw-io-on-mac-os-x-ie-equivalent-to-linuxs-o-direct-flag
>> for notes about the F_NOCACHE feature used. Same basic situation as
>> Solaris; there's an API, but PostgreSQL doesn't use it yet.
>
> Actually, on OSX 10.5.8, o_dsync and fdatasync aren't even available.
> From my run, it looks like even so regular fsync might be better than
> open_sync.
But I think you need to use fsync_writethrough if you actually want durability.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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