From: "Denie Andriessen" <denie@bokxing.nl>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] LVM snapshot - "dd" file size
Date: Wed, 16 Apr 2008 23:36:49 +0200 [thread overview]
Message-ID: <003e01c8a009$fa453ad0$0132a8c0@denie> (raw)
In-Reply-To: 20080416210439.GA31820@pretender.frop.net
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: <dave@frop.net>
To: "LVM general discussion and development" <linux-lvm@redhat.com>
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/
>
next prev parent reply other threads:[~2008-04-16 21:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-16 14:59 [linux-lvm] LVM snapshot - "dd" file size Thomas Bellembois
2008-04-16 21:04 ` dave
2008-04-16 21:36 ` Denie Andriessen [this message]
2008-04-17 12:44 ` Thomas Bellembois
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