sfdisk don't like partitions - want to dump another hard drive to restore software RAID

Question

I'm using Cent OS 6.5.

I have two Hard Drive which are exact copies of each others (/dev/sda and /dev/sdb).

/dev/sda failed and had to be replaced.

I am trying to copies everything from /dev/sdb to /dev/sda.

When I try to execute the command sfdisk -d /dev/sdb | sfdisk /dev/sda, I get the following result :

Checking that no-one is using this disk right now ...
OK

Disk /dev/sda: 121601 cylinders, 255 heads, 63 sectors/track
Old situation:
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sda1          0       -       0          0    0  Empty
/dev/sda2          0       -       0          0    0  Empty
/dev/sda3          0       -       0          0    0  Empty
/dev/sda4          0       -       0          0    0  Empty
New situation:
Units = sectors of 512 bytes, counting from 0

Device Boot    Start       End   #sectors  Id  System
/dev/sda1   *      4096  41947135   41943040  fd  Linux raid autodetect
/dev/sda2      41947136 1952468991 1910521856  fd  Linux raid autodetect
/dev/sda3     1952468992 1953519615    1050624  82  Linux swap / Solaris
/dev/sda4             0         -          0   0  Empty
Warning: partition 1 does not end at a cylinder boundary

sfdisk: I don't like these partitions - nothing changed.
(If you really want this, use the --force option.)

parted -l returns the following :

Model: ATA Hitachi HUA72201 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start  End  Size  Type  File system  Flags


Model: ATA ST1000DM003-9YN1 (scsi)
Disk /dev/sdb: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos

Number  Start   End     Size    Type     File system     Flags
1      2097kB  21.5GB  21.5GB  primary  ext4            boot, raid
2      21.5GB  1000GB  978GB   primary  ext4            raid
3      1000GB  1000GB  538MB   primary  linux-swap(v1)

I have also tried sgdisk -R=/dev/sda /dev/sdb but the command returns absolutely no output or error message.

What should I be doing?

Answer 1

The requirement to align to cylinder boundaries has been gone for a long time now. With the introduction of drives with 4k blocks and SSDs with 128k erasure blocks it has become neccessary to align to multiples of those instead. An alignment to 1MiB boundaries seems to become the new standard and is what DI uses in squeeze.

Source

You can use the --force option if you think that the alignment is OK.