From owner-freebsd-fs@freebsd.org Thu Jun 14 06:28:23 2018 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9E050100579F for ; Thu, 14 Jun 2018 06:28:23 +0000 (UTC) (envelope-from ben.rubson@gmail.com) Received: from mail-wr0-x230.google.com (mail-wr0-x230.google.com [IPv6:2a00:1450:400c:c0c::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 0C18F76DCE for ; Thu, 14 Jun 2018 06:28:23 +0000 (UTC) (envelope-from ben.rubson@gmail.com) Received: by mail-wr0-x230.google.com with SMTP id a12-v6so5081087wro.1 for ; Wed, 13 Jun 2018 23:28:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date :content-transfer-encoding:message-id:references:to; bh=I1c9yciTg+yk7jA8C6UNfGpN57tIqLXVdGl3CqeunUM=; b=ZZgen8B/HdU/MH/W59jvF69JfeRMtpfuwcZElaEIall7p6MWVA6PTEMQ4NDHrgFcnA ZVYnlIXR0COQBxcipbT/eOMBNHo8is9O4ERhG1FZ6ubxOJbPt5xDOu9fevQGm+wu0qvQ Ia9Hzls0xHYF0GIwXEGjmEK1Eh9I9rJWpRbL7n/vahHino12GWqjgPYr1+Id8dOsxng7 m4jLsBX6MNljUS9Rzf9qTe6F8Uk2XuvTNTmyAIANCZI8G4Y2J3gWIrTQlhYIQvfdl3Pq Uc0YHqy1yB6QuuZGa3nZvDTCqipzY15a29kdPAb6GcLvid+QuYKguXXKz63hAH3rcjLN zURA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date :content-transfer-encoding:message-id:references:to; bh=I1c9yciTg+yk7jA8C6UNfGpN57tIqLXVdGl3CqeunUM=; b=s179UvjYf4KyvdP0A9gegrY+j2OlKsxai8FmeSPY04HMeDKOE69NdXL7qz1YrwpBPa Mp51XdFb0IQ77kBOMCvMs0kDbVpH+QCVZ6Hy22OnRdgz//MeeYakHKk/k090BZs4WwJY Xql9aGg4251BTlpm41C3rs+ndDXqELyJaLEwhrHSvYUj2CB+Dje2iwPL9g5VXk25dwNv QSnSTudhjIZf3DQfSiB1MtexvAvhvv03T1wjtH3zPx+QYLkdULhaqM2Dp5mkYiaXeZu0 Ai8+0I8oke8LVvW2zDYBJUdM9QJKDE2qbejgYc9W1V20cxanUIT0L9UDcflsQrRNXbT+ BJqQ== X-Gm-Message-State: APt69E2cFrweB6C+qZuqx5Vgnuf3Bb+O5tbVDvadpZd0aOeE64oJG+nw q/Hos8IYNxOrtje29vmJTbjOOD4z X-Google-Smtp-Source: ADUXVKKa6WDA9rbyDJunrcvPg/+Dg042pfEiLZythi7pTsUYLsC/FqlZXK3QJZrxqH+/Zx/RMwZV9Q== X-Received: by 2002:adf:a686:: with SMTP id t6-v6mr899262wrc.51.1528957700919; Wed, 13 Jun 2018 23:28:20 -0700 (PDT) Received: from bens-mac.home (LFbn-NIC-1-162-72.w2-15.abo.wanadoo.fr. [2.15.243.72]) by smtp.gmail.com with ESMTPSA id b204-v6sm4732164wmh.22.2018.06.13.23.28.19 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 13 Jun 2018 23:28:20 -0700 (PDT) Content-Type: text/plain; charset=iso-8859-1; delsp=yes; format=flowed Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: What append when arc full From: Ben RUBSON In-Reply-To: <20180614054333.GA7053@io.chezmoi.fr> Date: Thu, 14 Jun 2018 08:28:18 +0200 Content-Transfer-Encoding: 7bit Message-Id: <842D180A-4725-418D-8EF8-639B50C8B72D@gmail.com> References: <20180613200700.GA3156@io.chezmoi.fr> <248ad0be-2002-89b5-0c1a-3ac73d493149@ShaneWare.Biz> <20180614054333.GA7053@io.chezmoi.fr> To: Tom Evans via freebsd-fs X-Mailer: Apple Mail (2.3124) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Jun 2018 06:28:23 -0000 On 14 Jun 2018 07:43, Albert Shih wrote: > I try last night, if I put > > vfs.zfs.arc_max=96G > > everything work fine (the sending). So I think that's the point. > > But my concern are what append if I shrink a little more the arc_max, let's > say 64G knowing I got < 30To of data. Does I'm going to loose lot of > performance ? The least recently used buffers of (meta)data (the colder ones) will be evicted to make room for the new needed (meta)data buffers. ZFS has a "constantly" background job running to keep ARC size under the limit. Performance will of course depend on the amount of hot (meta)data you play with. Perhaps you could benefit from setting a L2ARC with your 2 SSDs. Evicted buffers would then be stored there for faster access when needed. >> If you want to keep some ram free for your processes, then you can set >> vfs.zfs.arc_max to limit the ram used by ARC. On recent system versions >> you can change it dynamically using sysctl or you can set it in > > "dynamically" .... I though it's only can set at boot time I also have it in /etc/sysctl.conf on 11.0 systems, I think it was also the case with 10.3. Ben