On 06/05/2010 21:45, Nicolas Williams wrote:
On Thu, May 06, 2010 at 03:30:05PM -0500, Wes Felter wrote:
On 5/6/10 5:28 AM, Robert Milkowski wrote:
sync=disabled
Synchronous requests are disabled. File system transactions
only commit to stable storage on the next DMU transaction group
commit which can be many seconds.
Is there a way (short of DTrace) to write() some data and get
notified when the corresponding txg is committed? Think of it as a
poor man's group commit.
fsync(2) is it. Of course, if you disable sync writes then there's no
way to find out for sure. If you need to know when a write is durable,
then don't disable sync writes.
Nico
There is one way - issue a sync(2) - even with sync=disabled it will
sync all filesystems and then return.
Another workaround would be to create a snapshot...
However I agree with Nico - if you don't need sync=disabled then don't
use it.
Someone else mentioned that yet another option like sync=fsync-only
would be useful so all would be async but fsync() - but frankly I'm not
convinced as it would require a support in your application but at this
point you already have a full control of the behavior without need for
sync=disabled.
--
Robert Milkowski
http://milek.blogspot.com
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