what happens to pool if ZIL dies on ZFS v14

[Bryan Drewery]

> I was under the impression ZFS still managed to utilise the ZIL when a
> pool didn't have any "log" devices associated with it (possibly some
> sort of statically-allocated amount of RAM?)
>
> You can search the FreeBSD lists for people continually advocating
> vfs.zfs.zil_disable=1.  There's even a couple blog posts from engineers
> talking about how the only way to get their filers to behave decently
> was to disable the ZIL[1][2][3].  In most (every?) cases I've seen where
> someone advocates disabling the ZIL, pool details aren't provided, which
> leads me to believe their pools have no "log" devices.
>
> Here's a better way to phrase my question: does vfs.zfs.zil_disable=1 do
> anything if there aren't any "log" devices in use (in any pool)?
>
>
> [1]: http://jmlittle.blogspot.com/2010/03/zfs-log-devices-review-of-ddrdrive-x1.html
> [2]: http://blogs.sun.com/erickustarz/entry/zil_disable
> [3]: http://weblog.etherized.com/posts/130
>
>   

The ZIL is still used even without a dedicated log device. Disabling it 
is *stupid* in most cases.
Same goes for disabling the ARC.

There is a lot of FUD out there regarding ZFS tuning. The bottom line: 
don't tune; add more RAM.

Bryan