From owner-freebsd-questions@FreeBSD.ORG Tue May 6 23:08:43 2014 Return-Path: Delivered-To: freebsd-questions@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 ESMTPS id 18363908 for ; Tue, 6 May 2014 23:08:43 +0000 (UTC) Received: from mail.magehandbook.com (173-8-4-45-WashingtonDC.hfc.comcastbusiness.net [173.8.4.45]) by mx1.freebsd.org (Postfix) with ESMTP id E2CBCF4E for ; Tue, 6 May 2014 23:08:42 +0000 (UTC) Received: from [192.168.1.50] (Mac-Pro.magehandbook.com [192.168.1.50]) by mail.magehandbook.com (Postfix) with ESMTP id 3gNbyd5HFPzwP for ; Tue, 6 May 2014 19:01:13 -0400 (EDT) Date: Tue, 06 May 2014 19:01:13 -0400 From: Daniel Staal To: FreeBSD Questions Mailing List Subject: Re: Swap on ZFS Message-ID: <533C7DE184760EBA0552D45C@[192.168.1.50]> In-Reply-To: References: X-Mailer: Mulberry/4.0.8 (Mac OS X) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 May 2014 23:08:43 -0000 --As of May 6, 2014 2:21:43 PM -0500, David Noel is alleged to have said: > Is swap on ZFS still ill-advised? All the forum, list, and blog posts > I find say it's a no-go. Is this still the case? The idea behind it > not working is that ZFS needs memory to write to disk, so when you > need to swap (are low on memory) ZFS won't be able to write. > > I found some talk of having a tunable added as a workaround that would > reserve a certain amount of memory for ZFS so this wouldn't be a > problem, but have no idea if anyone's made any progress towards > implementing it. --As for the rest, it is mine. I haven't seen anything official, and it hasn't been that long (a couple of months - I don't think I've seen any major updates since that didn't have to do with OpenSSL) since I had a problem that locked up my machine for a day before I could fix it and give it some *other* swap, so I'll say: Yes. That said, if you don't use swap heavily it works: I didn't have trouble for several years before I started adding to the box's load and ran it out of RAM. Just make sure you have enough RAM to cover all normal requirements, and that extreme cases aren't very common or very extreme. Otherwise, give it a small dedicated swap drive/partition. (I put it on the same drive the ZIL - the ZIL will have a max defined size dependent on your RAM, so there was plenty of space on the SSD that would never be used.) Daniel T. Staal --------------------------------------------------------------- This email copyright the author. Unless otherwise noted, you are expressly allowed to retransmit, quote, or otherwise use the contents for non-commercial purposes. This copyright will expire 5 years after the author's death, or in 30 years, whichever is longer, unless such a period is in excess of local copyright law. ---------------------------------------------------------------