[CentOS] CF disks images and centos

Les Mikesell lesmikesell at gmail.com
Tue Nov 30 14:37:21 EST 2010

On 11/30/2010 1:13 PM, Robert Heller wrote:
> At Tue, 30 Nov 2010 12:26:04 -0600 CentOS mailing list<centos at centos.org>  wrote:
>> On 11/30/2010 12:10 PM, Brunner, Brian T. wrote:
>>>>> The size has changed. The original CF card was 7637M (255 heads/63
>>>>> sectors/928 cylinders)
>>>>> The new CF card is 8019M (255 heads/63 sectors/974 cylinders)
>>>>> I simply do "dd if=cf.img of=/dev/sde" to copy the images to CF.
>>>> ARG!!! Don't do this!  You really, really don't want to dd a
>>>> raw disk image (including mbr/partition table) to a
>>>> *different* geometry disk -- it does not matter what the
>>>> 'disk' tech is (IDE. SCSI, SATA, SSD, etc.).
>>> Even if the two disks have the same manufacturer and manufacturer part
>>> number, different firmware revisions can fail to boot after
>>> dd if=/dev/spinpoint.partnumber.fwrev1
>>> of=/dev/spinpoint.partnumber.fwrev2
>>> Been there, done that, got bit where the sun doesn't shine.
>>>> Partition the new disk with fdisk (or something like that),
>>>> then use mkfs to make the file systems than use dump/restore
>>>> to move the file systems.  Finally use grub-install (or lilo)
>>>> to install the boot loader.
>>> +1
>>> sfdisk -d /dev/olddisk>   /product/partition.layout
>>> dump (whatever)
>>> ...years later...
>>> sfdisk /dev/newdisk<   /product/partition.layout
>>> restore (whatever)
>>> grub-install (magic tbd)
>>> # SHIP IT
>> I'm not positive, but I'd expect clonezilla to get this right - and
>> probably be able to expand the partition after the copy for you.  Plus
>> it will save time compared to dd by not needing to copy unused disk
>> blocks and it can save a compressed image on a file server for repeated
>> cloning.
> Right.  clonezilla is much more than dd.  I would suspect that
> clonezilla is a bundling of sfdisk, dump/restore, and grub-install, or
> something link that.

Yes, dd is a worst-case fallback if it doesn't recognize the filesystem, 
and even then it would do each partition separately. Normally it would 
use partimage, partclone, or ntfsclone, automatically deciding which is 
best.  I don't think it ever uses dump or tar, but it would be kind of 
nice is someone added those as a restore approach inside the wrapper 
that does the partitioning and setup for quick bare-metal restores from 
live backups.

   Les Mikesell
    lesmikesell at gmail.com

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