On Sat, Jun 21, 2008 at 12:06:42AM -0700, Jeff Bonwick wrote:
> > Clever, but no it does not - the properties only apply to new I/O.
> 
> Nor should it.  The ARC and L2ARC are both physical caches, whereas
> ZFS datasets are logical.  There can be many-to-one mappings between
> datasets and cached blocks, whether because of snapshots (today) or
> deduplication (coming).  Trying to flush the ARC or L2ARC in response
> to turning off caching in a particular dataset would be like trying
> to flush physically tagged e-cache lines in respose to a process
> with shared memory segments exiting.

All true. However, we could (and should?) not check the caches if caching
is not enabled for the dataset. This would have a similar effect as flushing.

Adam

-- 
Adam Leventhal, Fishworks                     http://blogs.sun.com/ahl

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