Re: Can we trust fsync? - Mailing list pgsql-hackers

From Claudio Freire
Subject Re: Can we trust fsync?
Date
Msg-id CAGTBQpaU6ByOzrQTLBvD5mYq8RQm94RSic7Af794Djghg2tbYQ@mail.gmail.com
Whole thread Raw
In response to Re: Can we trust fsync?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Fri, Nov 22, 2013 at 1:16 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> The original mail was referencing a problem with syncing *meta* data
>> though. The semantics around meta data syncs are much less clearly
>> specified, in part because file systems traditionally made nearly all meta
>> data operations synchronous. Doing plug-pull testing on Postgres would not
>> test meta data syncing very well since Postgres specifically avoids doing
>> much meta data operations by overwriting existing files and blocks as much
>> as possible.
>
> True.  You're better off with a specialized testing program.  (Though
> now you mention it, I wonder whether that program was stressing metadata
> or not.)


You can always stress metadata by leaving atime updates in their full
setting (whatever it is for that filesystem).



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