Can fsync() ensure data is flushed to disk?

[wangqinghuan <10...@qq.com>]

hi
http://activemq.apache.org/artemis/docs/2.1.0/persistence.html.
This article  tells me that even after syncing from the operating system
there is no guarantee the data has actually made it to disk. we must disable
disk cache to ensure data integrity .
https://linux.die.net/man/2/fsync
This tells me that fsync() transfers  all modified in-core data of the file
referred to by the file descriptor fd to the disk device  so that all
changed information can be retrieved even after the system crashed or was
rebooted. This includes writing through or flushing a disk cache if present.
there are two different views in above 2 articles.What's correct?





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Re: Can fsync() ensure data is flushed to disk?

[Clebert Suconic <cl...@gmail.com>]

I will remove that from the docs...

In a previous version, we just had libaio to perform a write on Linux,
and never to call fdatasync... you would require to disable
write-cache to make sure the data would be synchronized on disk.

With the latest version we now call fsync...


you would save some resources by not using the write-cache non
necessarily. but it's not about the data being sync by itself.

On Tue, Jun 6, 2017 at 3:51 AM, wangqinghuan <10...@qq.com> wrote:
> hi
> http://activemq.apache.org/artemis/docs/2.1.0/persistence.html.
> This article  tells me that even after syncing from the operating system
> there is no guarantee the data has actually made it to disk. we must disable
> disk cache to ensure data integrity .
> https://linux.die.net/man/2/fsync
> This tells me that fsync() transfers  all modified in-core data of the file
> referred to by the file descriptor fd to the disk device  so that all
> changed information can be retrieved even after the system crashed or was
> rebooted. This includes writing through or flushing a disk cache if present.
> there are two different views in above 2 articles.What's correct?
>
>
>
>
>
> --
> View this message in context: http://activemq.2283324.n4.nabble.com/Can-fsync-ensure-data-is-flushed-to-disk-tp4727063.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.



-- 
Clebert Suconic