Questions about hard disks and dd?

[Paul Wahner]

Hello all,

I have a number of 2GB fast-wide diff. hard drives which I'm trying to write disk images to using dd.

Now I don't have identical disks but I do have what my HP Disk Upgrade Manual calls "functional and replacement equals". The drives I have are Seagate ST32171W and Seagate ST32550W. The diskinfo output of each of these disks is different, which would probably pretty much make my dd coping a wasted effort.

For example: (on my J210)
(Current working disk)
SCSI describe of /dev/rdsk/c0t6d0:
vendor: SEAGATE
product id: ST32171W
type: direct access
size: 2097342 Kbytes
bytes per sector: 512
rev level: HP03
blocks per disk: 4194685

(A disk I would like to copy to)
SCSI describe of /dev/rdsk/c0t5d0:
vendor: SEAGATE
product id: ST32171W
type: direct access
size: 2082636 Kbytes
bytes per sector: 512
rev level: HPC1
blocks per disk: 4165272

(Another disk I would like to copy to)
SCSI describe of /dev/rdsk/c0t5d0:
vendor: SEAGATE
product id: ST32550W
type: direct access
size: 2082636 Kbytes
bytes per sector: 512
rev level: HP10
blocks per disk: 4165272

Now my uneducated eye tells me the "rev level" plays a part in the formated size of the disk reported by diskinfo.

My first question, Is there a method by which I could "reformat" my blank disks to be able to get a matching result of current working disk?

With regard to dd, I have been booting the workstations to single user mode to do my dd copies to 4mm tape. Is this a necessary step or could I do the dd on the fly?

Thanks for your time!
Paul Wahner

[CHRIS_ANORUO]

Paul,

You can do dd in multi user mode (on the fly as you said).

[Victor BERRIDGE]

Hi Paul,
Im not sure reformating would help cancelling the ridicoulously small difference of size between you current disk and the others that will make dd unsuccessfull...
I would go for ignite make_recovery of the current disk and restore on an alternate, that will allow you to do all the dd you want after you have made the alternate your new primary disk.

Good luck
Victor

[Paul Wahner]

Victor,

At this point I don't have Ignite installed to use make_recovery though I am seriously considering this path.

Doesn't make_recovery check the size of the disk I would want to restore to? I guess I'm under the impression that make_recovery is a souped up version of copyutil and I know that copyutil is not forgiving if the original disk is different from the alternate. Is my impression of this incorrect???

Paul

[Victor BERRIDGE]

when you restore, there is 2 modes:
Batch, it will put everything back as found on the system when you generated the make_recovery.
Interractive, you will have to use this mode since you want it to restore on another disk..
Yes it will check the size, but it will also allow you to change the size of all the file systems and swap...
Thats why I thought this would be your solution. you could do a bit of cleaning up before backup, and restore on a disk slightly smaller, if it cant do it it will tell you by how much you will have to reduce...
So go and download it its free...
All the best
Victor

[Michael Lampi]

The dd method can be guaranteed to work only if
the target drive is at least the same size as
the source disk.

You are much better off using make_recovery.

To reformat the target drives to the same size
as the source drive might be possible, but
requires special SCSI tools to change the
number of spare blocks, etc. It also requires
the smaller drives to have enough spares that
it can give up for user-accessible space. I
do not think that you will find there are
29,000+ spare disk blocks on the smaller drive.

[Darrel Louis]

You will be better of with a Ignite recovery tape.
As the other members suggested.

About the "rev level"(firmware).
It could be that the firmware level is causing the differences in sizes. The firmware for disks or other parts are fixing several things.
Why don't you try upgrading the disks to the latest firmware level or equalize them.

[CHRIS_ANORUO · Accepted solution]

You can download and install the Ignite-UX software from this site: http://www.software.hp.com/products/IUX/

[Dan Hetzel]

Hi Paul,

'make_recovery' is the way to go as 'dd' requires the destination disk to be at least as large as the source disk.

Best regards,

Dan

[Dan Hetzel]

Hi Paul,

'make_recovery' is the way to go as 'dd' requires the destination disk to be at least as large as the source disk.

Best regards,

Dan

[jp]

I am trying to copy an op sys disk of 2gb to a 4gb (4.2) just for the extra space, and I have spare 4.2gb drives. If I dd the 2gb to the 4gb, what happens to the extra 2.2gb of space? How do I make it usable, how will SAM see it?
TIA,
jp

[Caesar_3]

Hello!

1. You can copy the disk with dd but because
the target is less than the source if you have
data in the end of the disk you will loose it.

2. You can use ignite to make recovery.

3. You can build the target disk partitions/LVM
and copy with cpio the data from partitions of src. disk to target disk.

Caesar

[V.Tamilvanan]

Hi,
If you do a dd of 2 GB source disk to 4 GB target disk. You will get all the data on the 2 GB disk but you will not be able to use the remaining 2 GB on the target disk.
Better u use ignite ux to do cloning , there u will be able to utilize the full 4GB disk.

HTH