From owner-freebsd-fs@FreeBSD.ORG  Fri Oct  4 09:50:31 2013
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTP id 1862AB27
 for <freebsd-fs@freebsd.org>; Fri,  4 Oct 2013 09:50:31 +0000 (UTC)
 (envelope-from zaphod@berentweb.com)
Received: from sam.nabble.com (sam.nabble.com [216.139.236.26])
 (using TLSv1 with cipher AES256-SHA (256/256 bits))
 (No client certificate requested)
 by mx1.freebsd.org (Postfix) with ESMTPS id F07692210
 for <freebsd-fs@freebsd.org>; Fri,  4 Oct 2013 09:50:30 +0000 (UTC)
Received: from [192.168.236.26] (helo=sam.nabble.com)
 by sam.nabble.com with esmtp (Exim 4.72)
 (envelope-from <zaphod@berentweb.com>) id 1VS21f-0000JP-KZ
 for freebsd-fs@freebsd.org; Fri, 04 Oct 2013 02:50:23 -0700
Date: Fri, 4 Oct 2013 02:50:23 -0700 (PDT)
From: Beeblebrox <zaphod@berentweb.com>
To: freebsd-fs@freebsd.org
Message-ID: <1380880223590-5848720.post@n5.nabble.com>
Subject: Questions re swap-on-zfs
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 04 Oct 2013 09:50:31 -0000

I have 2 swap devices on my system. #1-tank0/swap on ZFS, #2-/dev/ada0p1 on
SSD 1GB. I have some questions for swap-on-zfs:

1. I had read in the past that swap-on-zfs can cause instability if memory
gets used to full capacity. Is this still the case, or has that issue been
corrected? The reason I created swap-#2 is precisely for this purpose; a
small backup resource.

2. If the problem still persists, I would like to tweak the setup so that
swap-#2 is only used as last resort. I tried setting the priority (pri) in
fstab, but it does not seem to work - how can this be done?
/dev/ada0p1   none   swap   sw,pri=0   0  0
tank0/swap    none   zfs    sw,pri=9   0  0

3. Is it necessary for the data on swap to go through the Intent Log? I have
a separate ZIL device for tank0 pool. What risk is there if I disable the
log for the swap dataset? Is this done by modifying the "primarycache"
parameter for dataset?

4. Any other ideas to speed-up swap performance on tank0/swap?

Regards.



--
View this message in context: http://freebsd.1045724.n5.nabble.com/Questions-re-swap-on-zfs-tp5848720.html
Sent from the freebsd-fs mailing list archive at Nabble.com.