On Mar 12, 2007  04:27 +0100, Jan Engelhardt wrote:

Assume this partition table on my current HD:

	Disk /dev/hdc: 251.0 GB, 251000193024 bytes
	255 heads, 63 sectors/track, 30515 cylinders
	Units = cylinders of 16065 * 512 = 8225280 bytes
	
	   Device Start  End      Blocks   Id  System
	/dev/hdc1   1     33      265041   82  Linux swap / Solaris
	/dev/hdc2  34  30515   244846665    5  Extended

That is, 255 * 63 * 30515 * 512 == roughly 251 GB.

Now, if this disk was copied byte per byte (/bin/dd) to a
4096-based disk, and Linux would start using a sector size of
4096

The easy answer is "don't do that".  You should make a new partition
table on the 4096-byte sector drive (each of the partitions at least
as large as the old ones), and then copy the content of each of the
partitions separately onto the new disk.

Although I would not mind the 2 TB, the partition table would
read quite differently (note the Blocks column which is
multiplied by 4 (512x4=4096))

           Device Start  End      Blocks   Id  System
        /dev/hdc1   1     33     1060164   82  Linux swap / Solaris
        /dev/hdc2  34  30515   979386660    5  Extended

Which would mean that the swap partition reaches into the real
data partition and would corrupt it.

In the same way you can't copy raw disks from one vendor's RAID 5
array and put them into another vendor's (or even model's) RAID 5 array,
or you can't do a raw copy of a partitioned disk and expect it to
suddenly become an LVM volume, you can't do raw disk copies between
drives with different sector size.

You also won't be able to use a copy of an ext3 filesystems with 1kB
blocksize onto a 4kB sector size device - the ext3 code will detect
this and refuse to mount.  At that point you need to do a tar/untar
(or whatever) to copy the data instead of a raw partition copy.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.