Robert -
This isn't surprising (either the switch or the results). Our long term
fix for tweaking this knob is:
6280630 zil synchronicity
Which would add 'zfs set sync' as a per-dataset option. A cut from the
comments (which aren't visible on opensolaris):
sync={deferred,standard,forced}
Controls synchronous semantics for the dataset.
When set to 'standard' (the default), synchronous
operations such as fsync(3C) behave precisely as defined
in fcntl.h(3HEAD).
When set to 'deferred', requests for synchronous
semantics are ignored. However, ZFS still guarantees
that ordering is preserved -- that is, consecutive
operations reach stable storage in order. (If a thread
performs operation A followed by operation B, then the
moment that B reaches stable storage, A is guaranteed to
be on stable storage as well.) ZFS also guarantees that
all operations will be scheduled for write to stable
storage within a few seconds, so that an unexpected
power loss only takes the last few seconds of change
with it.
When set to 'forced', all operations become synchronous.
No operation will return until all previous operations
have been committed to stable storage. This option can
be useful if an application is found to depend on
synchronous semantics without actually requesting them;
otherwise, it will just make everything slow, and is not
recommended.
There was a thread describing the usefulness of this (for builds where
all-or-nothing over a long period of time), but I can't find it.
- Eric
On Mon, Aug 07, 2006 at 06:07:53PM +0200, Robert Milkowski wrote:
> Hello zfs-discuss,
>
> Just a note to everyone experimenting with this - if you change it
> online it has only effect when pools are exported and then imported.
>
>
> ps. I didn't use for my last posted benchmarks - with it I get about
> 35,000IOPS and 0.2ms latency - but it's meaningless.
>
>
>
> --
> Best regards,
> Robert mailto:[EMAIL PROTECTED]
> http://milek.blogspot.com
>
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss@opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
--
Eric Schrock, Solaris Kernel Development http://blogs.sun.com/eschrock
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