HEADS UP: New ZFS in the tree.

Wes Morgan morganw at chemikals.org
Sun Dec 7 04:41:19 PST 2008

On Sun, 7 Dec 2008, Peter Schuller wrote:

>> While you are talking about it: Does anyone know if the fsync blocks
>> until the data is really stable on the device or if it simply returns
>> when ZIL is disabled?
>> In my understanding the topmost block would need to be written for the
>> "commit" to be on disk.
> My understanding is that disabling the ZIL *will* break the semantics
> of fsync().
> The claim of "always consistent on disk" is not violated and is still
> maintained, since consistency refers to ZFS' internal consistency.
> The tuning guide someone posts a link to later in this thread has
> specific claims about this IIRC; such as NFS breaking (because
> fsync-on-close semantics mandated by NFS, among other things, will not
> be honored).

And this would also apply to databases that rely on fsync() for ACID 
compliance, such as postgres, right?

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