From owner-freebsd-fs@FreeBSD.ORG Tue Jul 16 13:28:12 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 3CA77AED for ; Tue, 16 Jul 2013 13:28:12 +0000 (UTC) (envelope-from feld@freebsd.org) Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by mx1.freebsd.org (Postfix) with ESMTP id 1593F6E3 for ; Tue, 16 Jul 2013 13:28:11 +0000 (UTC) Received: from compute1.internal (compute1.nyi.mail.srv.osa [10.202.2.41]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id AB0A820DD9 for ; Tue, 16 Jul 2013 09:28:10 -0400 (EDT) Received: from web3 ([10.202.2.213]) by compute1.internal (MEProxy); Tue, 16 Jul 2013 09:28:10 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=message-id:from:to:mime-version :content-transfer-encoding:content-type:in-reply-to:references :subject:date; s=smtpout; bh=mddd0WTAXXbCrTook0FGMu24DSc=; b=n3z nXv31hzgW/bg+2diuacmdfPn4LE+Kw0+2hiqWqlevweTPJN6AQj2Yl/bKz3mHthp 8IiF87O7XpFSqVnf+HSbYl3Fe6wIkKrLl7PRI9bFt9XFTM5D8IumluWZcWO1vb8Z 71s6yVTVCJ7hIZw/d8eJi+isq7XnxoXbTEgXE0Pc= Received: by web3.nyi.mail.srv.osa (Postfix, from userid 99) id 8A324B00003; Tue, 16 Jul 2013 09:28:10 -0400 (EDT) Message-Id: <1373981290.1619.140661256268541.61E5E601@webmail.messagingengine.com> X-Sasl-Enc: JPgyAKDUogswwdNuepDwVrkVBIyjJ64y7196KMhTC34O 1373981290 From: Mark Felder To: freebsd-fs@freebsd.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain X-Mailer: MessagingEngine.com Webmail Interface - ajax-bdcdd1cb In-Reply-To: <51E54799.8070700@digsys.bg> References: <51E5316B.9070201@digsys.bg> <20130716115305.GA40918@mwi1.coffeenet.org> <51E54799.8070700@digsys.bg> Subject: Re: ZFS vdev I/O questions Date: Tue, 16 Jul 2013 08:28:10 -0500 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: Tue, 16 Jul 2013 13:28:12 -0000 On Tue, Jul 16, 2013, at 8:16, Daniel Kalchev wrote: > > Could this be DDT/metadata specific issue? Is the DDT/metadata > vdev-specific? The pool initially had only two vdevs and after vdev 3 > was added, most of the written data had no dedup enabled. Also, the ZIL > was added later and initial metadata could be fragmented. But.. why > should this affect writing? The zpool is indeed pretty full, but > performance should degrade for all vdevs (which are more or less equally > full). > I don't want to put you down the wrong path, but you're right -- the zpool is pretty full, and zfs is known to have issues writing when above ~80%. There's another thread where this was discussed briefly. However, you have quite a large pool so I find it hard to believe that your 3.45TB free is so fragmented that zfs is having issues choosing where to write. It's certainly possible, though. Hopefully someone will drop in their 2c as well