should raw root/boot copy go on internal or external disk?

[Paul Senior_1]

I am upgrading an alk370 machine.
It has 1x2gb internal disk and, when finished, will have 2x hass/jamaica external disk arrays with 8x9gb disks in each + mirroring on 2 separate buses.

As I want maximum cover on this machine, I intend to use dd to do a raw copy of the boot/root internal disk. The question is - should this copy go on an external disk or another internal disk (what are the pro's and cons of each?).

A separate question also - is it advisable to mirror the root disk AS WELL as creating a raw copy of the root/boot disk?

[Bernhard Mueller · Accepted solution]

Paul,

the method to use dd for a disk copy of the boot disk is only of use if that is the *same* disk and the boot disk can easily be swapped, ie. replaced with the dd'ed clone in the *original* slot or rather with the original HW path.

This is possible if you use a HASS disk as a boot disk, since the SCSI target id is set by the dip switch at the back of the enclosure. For the 2GB internal disks of the K's the target is set using jumpers and moreover you have to open the machine and remove/re-attach some cabling....

Usually it is better to mirror root disks and create ignite recovery tapes on a regular basis to cover contingencies.

If you install on disks in the HASS and mirror to another one in the HASS you my replace failed boot disks without interruption.

Regards,
Bernhard

[Paul Senior_1]

thanks Bernhard - this is useful.
So it sounds like there is no reason to use the internal disks at all - if they are hard to replace then they are best not used.

Are there are repercusions from booting from an external disk? (as well as the obvious benefits?)

So assuming my solution is all based on external HASS array disks:-
Would you advise a raw copy of the boot disk or mirroring, or even both?