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On 16 May 2011 07:31, Adam Carter <adamcarter3@×××××.com> wrote: |
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> |
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>> > To check my understanding - would it be correct to say that; |
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>> > 1. Using dd to copy the first 512 bytes (MBR) is ALL that is needed to |
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>> > setup the partitions - that is i wont need to run fdisk etc afterward. |
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>> |
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>> This is correct if you only have primary partitions. It will not copy the |
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>> extended partition and any logical partitions in it. They reside in the |
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>> first |
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>> sector of the extended partition, which is not a boot sector, but contains |
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>> the |
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>> logical partition table. (I found this out the hard way!) |
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>> |
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>> Have a look at this to see how you can back up the extended partition |
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>> tables |
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>> with sfdisk (there's more than one of these, if you have more than one |
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>> logical |
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>> partition) : |
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>> |
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>> http://www.partimage.org/Partimage-manual_Backup-partition-table |
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>> |
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>> |
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>> > 2. Using dd in this way of course will not update the kernel's knowledge |
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>> > of |
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>> > the partition table so a partprobe is necessary |
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>> |
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>> Yes, or a reboot. |
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>> |
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>> |
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>> > 3. When using fdisk to write a partition table and exit, it calls a |
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>> > re-read |
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>> > of the partition table by the kernel so any changes should be ready |
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>> > straight away. (there's a message about calling ioctl when it exits - so |
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>> > i |
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>> > guess that is the update) |
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>> |
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>> They are ready (i.e. written) but not yet read by the OS. Tools like |
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>> gparted |
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>> (part)probe the device to re-read the partition table after saving changes |
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>> to |
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>> disk. |
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> |
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> Thanks Mick. Great info, esp about the extended partitions. Fortunately, I |
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> dont have any on this disk but good to know. |
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OK, this is what I would do: |
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dd over the MBR (bs=512 count=1). This will bring over the bootloader |
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code and the primary partition table. Any primary partitions you had |
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will be copied over, same number and same size. |
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Then reboot. This will read the new primary partition table. |
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Then run your dd command on the respective partition. It should not |
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error out on the first bs, but I suggest that you also add |
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conv=notrunc. and perhaps conv=notrunc,noerror. The notrunc is |
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necessary to copy all sectors, otherwise dd will stop as soon as it |
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reaches unused sectors and truncate the test of the copy. The noerror |
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will make it carry on even if there are read errors. In this way what |
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you get on the new disk should be identical bit by bit with what's on |
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the old disk including empty space. |
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Then you can use gparted and resize partitions, add new ones, etc. |
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BTW do not resize ntfs partitions unless you have booted into them |
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defragged them first. |
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Let us know how it goes. |
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-- |
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Regards, |
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Mick |
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