From owner-freebsd-fs@FreeBSD.ORG Sat Oct 20 07:18:13 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 4401865E for ; Sat, 20 Oct 2012 07:18:13 +0000 (UTC) (envelope-from david@wimsey.us) Received: from mail-vb0-f54.google.com (mail-vb0-f54.google.com [209.85.212.54]) by mx1.freebsd.org (Postfix) with ESMTP id E2AE78FC0C for ; Sat, 20 Oct 2012 07:18:12 +0000 (UTC) Received: by mail-vb0-f54.google.com with SMTP id v11so1666109vbm.13 for ; Sat, 20 Oct 2012 00:18:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=from:content-type:content-transfer-encoding:subject:message-id:date :to:mime-version:x-mailer:x-gm-message-state; bh=D3VCcTqVOTY5RKZTCtAwu78nTwxcYQVjQETJgpaK08M=; b=nfZuTetAgpnHJrvo4MLFaElLigUattrvPIycZqlu553///7HhLfzvSzMOcGFj0UCr1 XlNqlvfwpLbxAy7C+7L48SKQrzWuC/YmM5YYMwxKDaMzhkzFZX7FI/BoWvj89L7Jc4dW J8IdCtBsuj1vKp7sIJfpdjFqrgkI6ZkX6vunDOpWqfaZgAHVmmizJQCrJGsQtWbruefo D+hjbeF1D8SU7tvkrSyvKojyqu4CnHmrsSF44h2eZmN8CF+I8zt9knii/kVTn1Z2+ZYs DpqyMNSpf6vTzyHSKOq6JYGuRwz8fc+Lw1N/S1pZUErvk96tUhmEPLQAqFGkOjhm7qdT TJPA== Received: by 10.58.171.4 with SMTP id aq4mr4842162vec.14.1350717491881; Sat, 20 Oct 2012 00:18:11 -0700 (PDT) Received: from [10.27.1.242] (cpe-107-015-155-065.nc.res.rr.com. [107.15.155.65]) by mx.google.com with ESMTPS id g5sm3488104vez.6.2012.10.20.00.18.11 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 20 Oct 2012 00:18:11 -0700 (PDT) From: David Wimsey Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Subject: Memory consumption after turning off dedup Message-Id: <44510CBA-2D95-4BDF-8AEE-61727760321C@wimsey.us> Date: Sat, 20 Oct 2012 03:18:10 -0400 To: "freebsd-fs@freebsd.org" Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\)) X-Mailer: Apple Mail (2.1499) X-Gm-Message-State: ALoCoQmhZQ/guFZhucxvKiYeVLIYS+sRPqjcK92Ndu+DFzetO/dPKbN6t7LfJY9fsK4Dj/EE1t5Z X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Oct 2012 07:18:13 -0000 I've had dedup on for a while and everything was good until the feeble = machine I have as a file server couldn't deal with the memory = requirements of dedup. I solved the problem by adding more RAM, = imported the pools on the machine and turned off dedup. I had a ratio = of less than 2x, and the main savings were on virtual machine disks = which I want maximum performance for. Does the memory consumption due to the DDT go away when you turn dedup = off or do I need to do a send/recv on it? I assume that once the block is deduced and written to disk its not = really any different than a blocks associated with a snapshot, is that = correct? I also assume that there is no performance penalties on reads, only = writes since it (with dedup on) has to check the dedup table to see if = it is a duplicate, is that correct?