PU

Hi all,

I previously used to command:
dd if=/dev/hda1 of=/mnt/hdb1/safecopy

It finishes successfully so I assume I have a backup of my /dev/hda1
partition.

Using the following line:
ls /mnt/hdb1
and I see the file safecopy.

My question:
If hda crashes, do I merely replace the hdd, configure the drive similar the
crashed drive and issue something like:
dd if=/mnt//hdb1/safecopy of=/dev/hda1
to restore?

Am I better off having a duplicate copy of hda1 e.g.
dd if=/dev/hda1 of=/dev/hdb1
Then if I have a hda crash, I plug in hdb as hda and install a new hdd as
hdb and just make a copy of it again.

I googled, and although there is a lot of material regarding the above, I
cannot seem to find a straight forward answer.
Any answers appreciated.

Regards
Leigh

cc to leejen666@hotmail.com

Scott Lurndal

"PU" <leejen666@hotmail.com> writes:
>Hi all,
>
>I previously used to command:
>dd if=/dev/hda1 of=/mnt/hdb1/safecopy
>
>It finishes successfully so I assume I have a backup of my /dev/hda1
>partition.
>
>Using the following line:
>ls /mnt/hdb1
>and I see the file safecopy.
>
>My question:
>If hda crashes, do I merely replace the hdd, configure the drive similar the
>crashed drive and issue something like:
>dd if=/mnt//hdb1/safecopy of=/dev/hda1
>to restore?

If the partitions are identically sized, then yes.

If you want to check the correctness of your safecopy, use
$ mkdir -p /mnt/tmp
$ mount -o loop -t ext2 /hdb1/safecopy /mnt/tmp
(substitute appropriate filesystem type for ext2 as necessary)

You should then see a copy of your filesystem under /mnt/tmp.

$ umount /mnt/tmp # when done

>
>Am I better off having a duplicate copy of hda1 e.g.
>dd if=/dev/hda1 of=/dev/hdb1

No. If this were to work at all, you'd need to use
$ dd if=/dev/hda of=/dev/hdb bs=128K

But both drives would need to be identically sized (or hdb need
be larger - if larger extra space will be wasted)

Using hda rather than hda1 will capture the MBR which is required
for boot purposes.

It's better, albeit slower, to use cpio or tar or rdist to backup
a filesystem as this allows dissimilar hardware to be used.

After a crash, reinstall a clean distro on a new disk and restore from
your backup rdist/cpio/tar archive(s).

scott