[Sussex] Really Dumb dd question

[John Crowhurst]

> okay, so heres a question.
>
> lets say at 2am in the morning when all the boring services and users
> are not being utilised and the back is done we do the following
>
>
> dd if=/dev/hda of=/dev/hdb

What will happen would be a raw copy of disk a to disk b (thats
everything, partitions, empty space and all) It will do a complete
diskcopy, and disk b will look exactly like disk a.

If you only intend to make a backup of a filesystem, use cpio, cp or tar.

It would also be better if both drives were not mounted, in case data
changes on the disk and you end up with a corrupted backup.

> where /dev/hda1 is the active file system and /dev/hdb is never mounted.
> Im i mad or sane ?

Mad!

If you have a 4.5GB disk a, and a 9GB disk b, you will end up with two
disks that are 4.5GB (at least until the disk is repartitioned and
reformated)

If the disk you are copying from is larger than the disk you are copying
to, then you will end up with possible corrupted data.

-- 
FyreMoon
Under the moon, the chaos dragon flies.