From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m3GLbEV8008833 for ; Wed, 16 Apr 2008 17:37:14 -0400 Received: from mta-fe.casema.nl (cas-mta3-fe.casema.nl [83.80.1.28]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id m3GLaumX019911 for ; Wed, 16 Apr 2008 17:36:56 -0400 Received: from localhost (cas-filter5.mgmt.casema.nl [10.42.32.118]) by mta-fe.casema.nl (Postfix) with ESMTP id 3E50C3DB7 for ; Wed, 16 Apr 2008 23:36:50 +0200 (CEST) Received: from mta-fe.casema.nl ([10.42.32.28]) by localhost (cas-filter5.mgmt.casema.nl [10.42.32.211]) (amavisd-new, port 20024) with ESMTP id 9AVs1D3zXB3U for ; Wed, 16 Apr 2008 23:36:50 +0200 (CEST) Received: from denie (535484E6.cable.casema.nl [83.84.132.230]) by mta-fe.casema.nl (Postfix) with SMTP id 074E43DEB for ; Wed, 16 Apr 2008 23:36:49 +0200 (CEST) Message-ID: <003e01c8a009$fa453ad0$0132a8c0@denie> From: "Denie Andriessen" References: <48061439.6040001@gmail.com> <20080416210439.GA31820@pretender.frop.net> Subject: Re: [linux-lvm] LVM snapshot - "dd" file size Date: Wed, 16 Apr 2008 23:36:49 +0200 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; format="flowed"; charset="us-ascii"; reply-type="original" To: LVM general discussion and development A compressed dd can still be quite large, as there still might contain non zero values.. if you compress the image, a possible way to make the resulting files smaller is to: - do a: 'dd if=/dev/zero of=/dummyfile' on the filesystem first (you might want to use 'bs' and 'count' parameters) - if you topped off the disk, delete the all zero dummyfile. The zipped result might be smaller. (both with dd and with tar..) Regards, Denie ----- Original Message ----- From: To: "LVM general discussion and development" Sent: Wednesday, April 16, 2008 11:04 PM Subject: Re: [linux-lvm] LVM snapshot - "dd" file size > this has nothing to do with LVM. > > dd knows nothing about files, it just copies the entire device (or file or > whatever). > > tar will work, if you use the right command line switches. Search around > on the web for pointers on how to use it. > > Another intermediate way would be to compress the image you get with dd. > > On Wed, Apr 16, 2008 at 04:59:05PM +0200, Thomas Bellembois wrote: >> Hi! >> >> I am using LVM partitions on a Debian Xen system. >> I use LVM snapshots to clone and backup my virtual machines. >> >> I have noticed that the ISO file created with the "dd" command it much >> bigger that the partition used space (actually 4.7GB for the ISO - 500MB >> used space). No problem if I mount the LVM snapshot and "tar" all of the >> data. >> >> I have googled the question and read that "dd" also copy "not used >> space". >> Why is the ISO file so big ? Is the "tar" method less safe ? >> Is there a better solution ? >> >> Thanks for your answers. >> >> Regards, >> >> Thomas >> >> >> >> _______________________________________________ >> linux-lvm mailing list >> linux-lvm@redhat.com >> https://www.redhat.com/mailman/listinfo/linux-lvm >> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ >