From owner-freebsd-fs@FreeBSD.ORG  Tue Mar 11 16:09:07 2014
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 ESMTPS id C7CECBD6
 for <freebsd-fs@freebsd.org>; Tue, 11 Mar 2014 16:09:07 +0000 (UTC)
Received: from people.fsn.hu (people.fsn.hu [195.228.252.137])
 (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits))
 (No client certificate requested)
 by mx1.freebsd.org (Postfix) with ESMTPS id 7A72B97C
 for <freebsd-fs@freebsd.org>; Tue, 11 Mar 2014 16:09:06 +0000 (UTC)
Received: by people.fsn.hu (Postfix, from userid 1001)
 id 83F341330D2A; Tue, 11 Mar 2014 17:03:26 +0100 (CET)
X-Bogosity: Ham, tests=bogofilter, spamicity=0.014710, version=1.2.3
X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MF-ACE0E1EA [pR:
 6.8671]
X-CRM114-CacheID: sfid-20140311_17032_1BB92BBD 
X-CRM114-Status: Good  ( pR: 6.8671 )
X-DSPAM-Result: Whitelisted
X-DSPAM-Processed: Tue Mar 11 17:03:26 2014
X-DSPAM-Confidence: 0.8521
X-DSPAM-Probability: 0.0000
X-DSPAM-Signature: 531f33ce834741959520001
X-DSPAM-Factors: 27, From*"Nagy, Attila" <bra@fsn.hu>, 0.00069,
 Is+this, 0.00278, ZFS, 0.00439, Subject*ZFS, 0.00479,
 Received*online.co.hu+[195.228.243.99]), 0.00584,
 Received*[195.228.243.99]), 0.00584,
 Received*online.co.hu, 0.00584, a+server, 0.00584,
 Received*(japan.t, 0.00584,
 Received*(japan.t+online.co.hu, 0.00584,
 Received*japan.t, 0.00750,
 Received*japan.t+online.private, 0.00750,
 Received*online.private+(japan.t, 0.00750,
 Received*from+japan.t, 0.00750, do+some, 0.00750,
 files, 0.00968, zpool, 0.01000, Yesterday+I, 0.01000,
 42+42, 0.01000, file+system, 0.01000, file+system, 0.01000,
 is+empty, 0.01000, a+zpool, 0.01000, files+for, 0.01000,
 see+these, 0.99000, directories, 0.01206,
X-Spambayes-Classification: ham; 0.01
Received: from japan.t-online.private (japan.t-online.co.hu [195.228.243.99])
 by people.fsn.hu (Postfix) with ESMTPSA id 4907D1330D1E
 for <freebsd-fs@freebsd.org>; Tue, 11 Mar 2014 17:03:25 +0100 (CET)
Message-ID: <531F33CD.8080005@fsn.hu>
Date: Tue, 11 Mar 2014 17:03:25 +0100
From: "Nagy, Attila" <bra@fsn.hu>
MIME-Version: 1.0
To: FreeBSD FS <freebsd-fs@freebsd.org>
Subject: ZFS eats memory/L2ARC while doing nothing?
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.17
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: Tue, 11 Mar 2014 16:09:07 -0000

Hi,

Yesterday I have created a server with stable/10@r262152.
Made a zpool on it and left it running.

The whole file system had only some empty directories (needed to 
populate it later for storage) and some programs, which do some reads on 
it (stat'ing files for existence).

Today, I can see these graphs:
https://lh3.googleusercontent.com/-CY8hLr7s6DY/Ux8xgqolTuI/AAAAAAAAKec/5gR99PIhPYw/s800/zfs_mem-day.png
https://lh6.googleusercontent.com/-gbUzPy5U8ko/Ux8xeKOq_zI/AAAAAAAAKeU/ZFpZx3zE4I4/s800/memory-day.png
https://lh5.googleusercontent.com/-KT7DiptLwEA/Ux8xbMXZ9NI/AAAAAAAAKeM/x2ZbHUJVvug/s800/iopsstat-day.png

So it seems ZFS did an average of 5 write IOPS and that L2ARC's side 
constantly grew to a whopping 6.2 GiBs (again: the file system is empty, 
only 42*42 directories were created on it).

Is this normal? What causes this?