Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932958Ab0FQPLD (ORCPT ); Thu, 17 Jun 2010 11:11:03 -0400 Received: from v002983.home.net.pl ([212.85.107.189]:55643 "HELO v002983.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932900Ab0FQPLA convert rfc822-to-8bit (ORCPT ); Thu, 17 Jun 2010 11:11:00 -0400 From: Hubert Kario Organization: QBS - Quality Business Software To: "David Pottage" Subject: Re: [PATCH][RFC] Complex filesystem operations: split and join Date: Thu, 17 Jun 2010 17:04:13 +0200 User-Agent: KMail/1.13.3 (Linux/2.6.33-ARCH; KDE/4.4.4; i686; ; ) Cc: "Nikanth Karthikesan" , "OGAWA Hirofumi" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Alexander Viro" , "Christoph Hellwig" , "Chris Mason" , linux-btrfs@vger.kernel.org References: <201006092035.46481.knikanth@novell.com> <201006151611.36443.knikanth@novell.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201006171704.14541.hka@qbs.com.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1834 Lines: 49 On Tuesday 15 June 2010 17:16:06 David Pottage wrote: > On 15/06/10 11:41, Nikanth Karthikesan wrote: > > I had a one-off use-case, where I had no free-space, which made me > > think along this line. > > > > 1. We have the GNU split tool for example, which I guess, many of us > > use to split larger files to be transfered via smaller thumb drives, > > for example. We do cat many files into one, afterwards. [For this > > usecase, one can simply dd with seek and skip and avoid split/cat > > completely, but we dont.] > > I am not sure how you gain here as either way you have to do I/O to get > the split files on and off the thumb drive. It might make sense if the > thumb drive is formated with btrfs, and the file needs to be copied to > another filling system that can't handle large files (eg FAT-16), but I > would say that is unlikely. > But you do have to do only half as much of I/O with those features implemented. The old way is: 1. Have a file 2. split a file (in effect use twice as much drive space) 3. copy fragments to flash disks The btrfs way would be: 1. Have a file 2. split the file by using COW and referencing blocks in the original file (in effect using only a little more space after splitting) 3. copy fragments to flash disks the amount of I/O in the second case is limited only to metadata operations, in the first case, all data must be duplicated -- Hubert Kario QBS - Quality Business Software 02-656 Warszawa, ul. Ksawerów 30/85 tel. +48 (22) 646-61-51, 646-74-24 www.qbs.com.pl System Zarządzania Jakością zgodny z normą ISO 9001:2000 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/