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

Sean Reifschneider jafo at tummy.com
Fri Jan 24 04:25:18 MST 2003


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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