[lug] Backup to 2nd HD with dd & rsync?

[Nate Duehr]

Ignore my other post.  (GRIN)

Sean (as usual) did a better job of explaining why dd is bad unless the
drives are identical.

Nate Duehr, nate at natetech.com
----- Original Message -----
From: "Sean Reifschneider" <jafo at tummy.com>
To: <lug at lug.boulder.co.us>
Sent: Friday, January 24, 2003 4:25 AM
Subject: Re: [lug] Backup to 2nd HD with dd & rsync?


> On Thu, Jan 23, 2003 at 08:07:45PM -0700, D. Stimits wrote:
> >and any PBR. You could remount read-only and probably get away with it.
>
> Unlikely, as he's trying to copy from a larger hard drive to a smaller
> one.  Unless he doesn't care about any data that resides in the last ~30%
> of the disc...
>
> Remember, hard drives don't necessarily allocate from the beginning and
> only us the end when earlier portions are unused...  Because of UFS
> cylinder groups, you can have a 90% empty file-system that has important
> data towards the end of the disc.
>
> DD is just the wrong tool for doing this, unless you have two discs of
> exactly the same size, and you shut down the system while copying...
>
> You really want to mount the second disc and then use the appropriate
> parameters to "rsync" to copy the data periodically.  You probably also
> want to unmount the disc when you aren't using it, so that a "rm -rf /"
> doesn't delete the backup copy as well...
>
> Sean
> --
>  I took a Meyers-Briggs personality test and came out an SMTP.
>                  -- Sean Reifschneider, 2000
> Sean Reifschneider, Inimitably Superfluous <jafo at tummy.com>
> tummy.com, ltd. - Linux Consulting since 1995.  Qmail, Python, SysAdmin
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