From owner-freebsd-stable@FreeBSD.ORG Mon Oct 13 21:25:24 2014 Return-Path: Delivered-To: freebsd-stable@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id B0AAE1F8; Mon, 13 Oct 2014 21:25:24 +0000 (UTC) Received: from orthanc.ca (orthanc.ca [IPv6:2607:f2f8:abf8::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "orthanc.ca", Issuer "orthanc.ca CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 772C6142; Mon, 13 Oct 2014 21:25:24 +0000 (UTC) Received: from [192.168.42.6] (d66-183-211-183.bchsia.telus.net [66.183.211.183]) (authenticated bits=0) by orthanc.ca (8.14.7/8.14.7) with ESMTP id s9DLPJUd041285 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Mon, 13 Oct 2014 14:25:22 -0700 (PDT) (envelope-from lyndon@orthanc.ca) Content-Type: multipart/signed; boundary="Apple-Mail=_F8830B7C-F8B5-4799-BA91-F14FEB3DD492"; protocol="application/pgp-signature"; micalg=pgp-sha1 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: getting to 4K disk blocks in ZFS From: Lyndon Nerenberg In-Reply-To: <201410132047.s9DKlGxD030176@gw.catspoiler.org> Date: Mon, 13 Oct 2014 14:25:19 -0700 Message-Id: References: <201410132047.s9DKlGxD030176@gw.catspoiler.org> To: Don Lewis X-Mailer: Apple Mail (2.1878.6) X-Spam-Status: No, score=0.4 required=5.0 tests=RDNS_DYNAMIC autolearn=no autolearn_force=no version=3.4.0 X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on orthanc.ca Cc: freebsd-stable@FreeBSD.org X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Oct 2014 21:25:24 -0000 --Apple-Mail=_F8830B7C-F8B5-4799-BA91-F14FEB3DD492 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Oct 13, 2014, at 1:47 PM, Don Lewis wrote: > Combine that with raidz and now the > overhead is about 40%. Ouch! But ~33 of that 40% is generic RAID overhead, and has nothing to do with = the 4K block size issue. (I.e., you would have 33% hit even if you were = running UFS on a three disk RAID5.) On any real-world system where you're running ZFS, it's unlikely the 4K = block overhead is really going to be an issue. And the underlying disk = hardware is moving to 4K physical sectors, anyway. Sooner or later = you're just going to have to suck it up. --lyndon --Apple-Mail=_F8830B7C-F8B5-4799-BA91-F14FEB3DD492 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- iQIcBAEBAgAGBQJUPEM/AAoJEG8PnXiV/JnU/fwP/i5a9ns87syp7G8aGMPVu7tk UMQilNakksxbIsVxmLk/qKgnktAaEX6e871KPSSAgB34EZkV5UCpdARMtCD1Vdmu iJVCdwqODtz2pgWYI7T1PYP2swnl2gpQvWt1SToMEITP0Tyqeqh184Cmj9fMoUI+ WwuIZ3emlF4VXBPCJxYDyR7BsbBEM8MMYzlwBxSGTTZzJoqoPwOMYrmx4fW3ALXe SnV7buUTSIMUYfIHfIlMDiOrfFS7/n8xy0cKFSyHCGW/uzTDVdfMEWzHZPc/ALQD 7+rQZRXTIHya/0xkksLnBTPZQ5o9/+PGZ5k0UIgGQCPFGXLSiRSHgsz/FGlg467i w+38g1933+iMTFoawmU4QV+YvrwWnddqcZbcqI6zM9kcCOy47LUJ7+oKildg421u AXOmVMEtJ6v27pK0xcBUqPGeP/GGzXvMZF4GV251iL7W7LcAqC8jLBVaRvT/uRYn U5h4IM4FDBQYsb3dW6N6mkjTXK3eo2hc7iwZnZCrA6qIxL5DqmbBxmrXC/wtuR/8 UFA7pS4qP+NKoTWXq7vxZhpm4KqZSBVCSoSQpNRUjhM/r++VUSRNsQYb01DSKj1F FOFCea+Opwgj1Na0/IWInecIeH9IcUQYyjD2y3l1aedhlvsmaFwkm1tF2J2FIu70 1jT9aCRZSkfcV9is5/nD =TiSk -----END PGP SIGNATURE----- --Apple-Mail=_F8830B7C-F8B5-4799-BA91-F14FEB3DD492--