Re: Direct I/O - Mailing list pgsql-hackers

From Andrew Dunstan
Subject Re: Direct I/O
Date
Msg-id 6afb4ce8-0b13-0278-7018-4c9f092148a7@dunslane.net
Whole thread Raw
In response to Re: Direct I/O  (Andrew Dunstan <andrew@dunslane.net>)
List pgsql-hackers


On 2023-04-09 Su 09:14, Andrew Dunstan wrote:


On 2023-04-09 Su 08:39, Thomas Munro wrote:
On Sun, Apr 9, 2023 at 11:25 PM Andrew Dunstan <andrew@dunslane.net> wrote:
Didn't seem to make any difference.
Thanks for testing.  I think it's COW (and I think that implies also
checksums?) that needs to be turned off, at least based on experiments
here.



Googling agrees with you about checksums.  But I'm still wondering if we shouldn't disable COW for the build directory etc. It is suggested at [1]:


Recommend to set nodatacow – turn cow off – for the files that require fast IO and tend to get very big and get alot of random writes: such VMDK (vm disks) files and the like.


I'll give it a whirl.



with COW disabled, I can no longer generate a failure with the test.


cheers


andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com

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