[CentOS] Transferring system to new drive

Lamar Owen lowen at pari.edu
Thu Sep 16 11:43:53 EDT 2010

On Tuesday, September 14, 2010 01:42:05 pm Robert Heller wrote:
> At Tue, 14 Sep 2010 13:19:16 -0400 CentOS mailing list <centos at centos.org> wrote:
> > What about doing all with dd ... If you have the second disk installed in
> > the same machine you can do "dd if=/dev/sda of=/dev/sdb" ort you can use
> > clonezilla is a live cd .

> dd only works IFF (!) the new drive is exactly the same size as the old
> drive.  Otherwise dd can be very bad.  This is a serious misuse of dd!

I routinely use dd for offline cloning to larger drives.  Works fine.  Just have to edit the partition table later, which isn't hard either, using several different open and closed source tools.  Using a blocksize of 8225280 makes it go faster (this being a remap CHS default for LBA drives, and a guaranteed greatest common divisor of any hard drive size of modern drives); but use fdisk -l (or equivalent parted command for non-MBR disks (like my laptop's GPT drive) to get the blocksize to a good value.

But having done a few now I vastly prefer doing it online using LVM.  No downtime, and it just works, including resizing, as long as you are going to a larger lv.

When a server simply has to have minimal downtime, LVM is worth its LoC in gold for this use.

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