Swap on ZFS Volume still panics?

[Pawel Jakub Dawidek]

On Wed, Sep 08, 2010 at 07:19:40PM +0300, App Deb wrote:
> Reading the wiki guides they mention the official way to add swap volumes on
> ZFS (set org.freebsd:swap=on etc..),
> 
> So I thought that it should work now, But I just got a panic in 8.1-RELEASE
> after a heavy memory situation that touched swap for the first time.

Swap on ZVOL is still not recommended. Where did you find information
that it now recommended? I can't find anything about swap on
http://wiki.freebsd.org/ZFS and on
http://wiki.freebsd.org/ZFSQuickStartGuide there is a note that it is
not recommended. Let me know where it is advised and I'll remove it or
add a note (if the documentation is mine).

> It is a hassle to add gmirror volumes for swap on full zfs systems, is there
> any workaround for this, or any news when a fix is coming or if it is
> coming?

I've no plans to fix it, maybe with ZFSv28 it will be easier to fix, but
this is really low priority. If you use full ZFS system the recommended
layout is described here:

	http://blogs.freebsdish.org/pjd/2010/08/06/from-sysinstall-to-zfs-only-configuration/

> If the current code procudes guaranteed panics with zfs swap, I think that
> every mention of swap on zfs should be removed from the semi-official wiki
> guides.

BTW. If this issue will be worked on in the future, it will be useful to
actually see your panic, backtrace and other debug info. To be honest, I
didn't expect it to panic, rather deadlock. Maybe panic is from deadlock
resolver? Hard to say without any debug info.

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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