From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (unknown [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 1FBBA1381FA for ; Sat, 17 May 2014 14:34:58 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id A7FBFE0C6B; Sat, 17 May 2014 14:34:52 +0000 (UTC) Received: from mx01.admin-box.com (mx01.admin-box.com [78.47.249.108]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 8AE2BE09EF for ; Sat, 17 May 2014 14:34:51 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mx01.admin-box.com (Postfix) with ESMTP id 0184C1E00A6 for ; Sat, 17 May 2014 16:34:50 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mx01.admin-box.com Received: from mx01.admin-box.com ([127.0.0.1]) by localhost (mx01.admin-box.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Z+WkVMeowLtN for ; Sat, 17 May 2014 16:34:48 +0200 (CEST) Received: from [192.168.0.138] (g231227255.adsl.alicedsl.de [92.231.227.255]) (Authenticated sender: daniel@troeder.de) by mx01.admin-box.com (Postfix) with ESMTPSA id D5D841E008C for ; Sat, 17 May 2014 16:34:47 +0200 (CEST) Message-ID: <53777386.3060305@admin-box.com> Date: Sat, 17 May 2014 16:34:46 +0200 From: Daniel Troeder User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] Copying data efficiently References: <20140517033357.GB3804@solfire> <201405170846.44414.michaelkintzios@gmail.com> <20140517075908.GD3804@solfire> <20140517105810.6c3f70b2@digimed.co.uk> In-Reply-To: <20140517105810.6c3f70b2@digimed.co.uk> X-Enigmail-Version: 1.6 OpenPGP: id=BB9D4887; url=http://keyserver.ubuntu.com:11371/pks/lookup?search=0xBB9D4887&op=get Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="GOGITfQDN3mWK0CocKp2v2Um4NufigV15" X-Archives-Salt: bc75c469-e0ff-477a-b615-960db0ca6339 X-Archives-Hash: 9c00dcc85f9ecf763ade9daaa66562c9 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --GOGITfQDN3mWK0CocKp2v2Um4NufigV15 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Am 17.05.2014 11:58, schrieb Neil Bothwick: > On Sat, 17 May 2014 09:59:08 +0200, meino.cramer@gmx.de wrote: >=20 >>> 3. Or you could use a sequential copy: >>> >>> cp -a /home /dev/sdb1/ && cp -a /home /dev/sdc1 >=20 >> 3.) The files I want to copy are in the size of some GB each. So the >> cache isnt big enough to hold ALL files for the second part. >=20 > Run the two copies simultaneously, start the first, switch to another > tab, start the second. That way the data for the second copy is always > the most recently cached. >=20 > However, I expect the speed limit here may be the USB bus unless you ar= e > using USB 3.0 drives on different buses. I was thinking about "how to make sure cache is used", and that two simultanious cp won't work, because the progress for the two cp will quickly diverge. But then I realized: there is no need to think about the read cache - the limiting factor is always the writing side, especially with USB! So IMO it doesn't matter at all how you do it! I guess two simultaneous cp will be the same as two sequential cp, except if you have two separate USB-buses. Usually you have just one externally connectible, use "lsusb -t" to check. If you have less that 2 times the size of your files, IMO simultaneous cp will be worse, because Linux (don't know if USB-subsystem or cp) creates big buffers when cp'ing (check with "free -m"), and you'll probably get into memory trouble. Greetings, Daniel PS: Quickest way is always to open USB-case and plug SATA cable from motherboard into drive. With >80GB it's always worth the trouble. --=20 Get my PGP key at: * http://keyserver.ubuntu.com:11371/pks/lookup?op=3Dget&search=3D0x837FB8B5= BB9D4887 * $ gpg --recv-keys --keyserver keyserver.ubuntu.com 0xBB9D4887 --GOGITfQDN3mWK0CocKp2v2Um4NufigV15 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTd3OGAAoJEJCOjMf/yVE3kZQQALJje/VekRQVPMarSjy15tAQ xrnvy9WpsI15k5VhcnnDTSltfkurRVU+GGkUwhd3yhIqNJcIEYndfdA/WuvgNSr7 tU/dib76yhE91UvDWmOmZ4f/6bxXHM8dEAr4WpYh8gRBc1PNo7vRbs14y877o94a IWdgwKzm6JwzGQg0JwbDKIx2t25PD/m4XNfEQFB3rK3C3XvwzU8wfMooQA8B7D6r LcC4AV40whuMlVWTJlUFPDWqyFHTwHg+AdvYuzygwAmHW9IF+TA55TlAbyuH5sg0 6eVAEviV+TvW5eaEBD2VVla7g0RChI0+Ahjz7OcBAjrLEijT2+BHDMpA5GiJNWaq P2OkFbH/35Mkf4mbMICRSio7iWsoX/vIUEo9TrlP4tVySHmQPmUMkyaLDJv8/5S+ ErawzuouM8VYJ+s17OtV6N6++EjnpwV/6tpNs5utNE01CgH+oUXvhDCyd1V2Up5K VidHBslVgQd1UCsIvDanxsU13EF4IBtrKjMPLDIOsXMfBvBiYgf3+XORPOs9OU1/ J2ffBXimyq9p3yUG79RKcONZYalSVaA1dXO9oBvmLeu+7td8V7Z3yP4GWvS4Z6I2 13vmdLJxpRMA1JCraby9YnRk8PlIT6kzjb2ljwjTo2zBY0SosSPv0OjA7ZqDgUOm ulIIgJkQMqut/Zrb/RYT =+SCl -----END PGP SIGNATURE----- --GOGITfQDN3mWK0CocKp2v2Um4NufigV15--