full backup remotely?

[Michael Ben-Nes]

To avoid changes on the fly its possible to use snapshot.

I am wondering, what will happen if ill feed dd through gzip. Will it
compress the empty spaces ?

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Michael Ben-Nes - Internet Consultant and Director.
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On Thu, Dec 31, 2009 at 1:03 AM, Tzafrir Cohen <tzafrir at cohens.org.il>wrote:

> On Thu, Dec 31, 2009 at 12:35:48AM +0200, sammy ominsky wrote:
> > On 31/12/2009, at 00:27, Hetz Ben Hamo wrote:
> >
> > > doing the backup. dd is nice, but that will copy also the empty space
> > > (although it won't have impact on the size of the backup, it will have
> an
> > > impact on the time it takes).
> >
> > dd has a --sparse flag which makes it not copy empty space.
>
> I don't see such a flag in the man page.
>
> partimage avoids copying any "free" block (block marked as free by the
> file system). If that block also happens to be zeroed out, dd is not
> aware of such details. And frankly can't safely be aware of them if Hetz
> want to copy a mounted partition.
>
> Also note that if you use dd to copy a mounted partition, you copy
> different parts of it in different times. This is tricky at best. Unless
> you e.g. use an LVM with a snapshot.
>
> tar (or any other backup of files) is safer. Even there you don't get a
> complete snapshot of the system. But at least every file is valid.
>
> --
> Tzafrir Cohen         | tzafrir at jabber.org | VIM is
> http://tzafrir.org.il |                    | a Mutt's
> tzafrir at cohens.org.il |                    |  best
> ICQ# 16849754         |                    | friend
>
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