Using dd to clone a drive [fast & simple]

Gentree · Last edited by Gentree on Wed Jun 22, 2005 2:36 pm; edited 2 times in total

After buying a new HD I wish to move the whole contents of my current drive to a new drive : mbr, partition table, partitions (mixed ntfs ext3 R4), the lot.

The disks are similar 80G / 120G Seagate IDE.

Is it feasible to just do a byte copy using dd to clone the old disk?

nixnut · Posted: Fri Apr 29, 2005 7:36 pm Post subject:

I don't think so. Since they're different sizes, sectors and cylinders would be different. I'm not sure, but I think you'd end up with a partition table that has nothing to do with the rest of the data on your disk, even if it ended up being a valid partition table, which I doubt.
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Sm1 · Posted: Fri Apr 29, 2005 8:06 pm Post subject:

Look into using partimage. I have used it to make partition images for drives, but i'm not sure if it will work for an entire drive

r3pek · Posted: Fri Apr 29, 2005 9:56 pm Post subject:

yes i can.... a simple

Gentree · Posted: Fri Apr 29, 2005 10:31 pm Post subject:

Thanks ,

that's even better/simpler than I expected. I just did the filrst 18M (7 min 50 = 72M/s ave r/w nice)

after that I tried parted to see the partitions and it looks good, but I get an error msg from parted.

Gentree · Posted: Sat Apr 30, 2005 8:06 am Post subject:

Yesss!

perfect clone.

All I needed to do was edit grub.conf and /etc/fstab on the new disk and c/hdc/hda/g

Its quite wierd to be running an identical system knowing its on other drive. Anyway I'm posting from the new system so all looks to be perfect. (Have not tried the win2k boot yet)

One point worth noting: 86 min for whole 80G drive. This is much slower than my first copy of 18G in 7.5 min , so it would seem to be a lot faster to define a large block size (within RAM limits) as I did in my first attempt.

@r3pek: it would be interesting to see if this gives an increase over a network but if you are on std 100Mb ethernet it may not be significant.

Thanks for your help anyway.

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r3pek · Posted: Sat Apr 30, 2005 6:37 pm Post subject:

It saves me all the trouble of open one server, put a new scsi card on it, add the new disc, make the copy, remove the disc, remove the scsi card, close the server and put the disk on the other server

lemino

Hi. I used the command

dd if=/dev/hda of=/dev/hdb

and it seems as if it has worked out well. A clone is created, and allthough it doesn't behave in the exaktly same manner as the old one, it works. For some reason it hangs on shutdown though... The problem is that I would like to resize the root-partition on my new drive (seagate 120) since it has not only take the content of the old disks (seagate 20) root-partition, but also its shape and size. Thus I'm left with one boot-partition, swap and a small root on my new drive + lots of free space I can't use. I have tried to make the reiserfs-root consume the remaining free space without success. Any tips?

syg00 · Posted: Wed Jun 22, 2005 1:15 pm Post subject:

I don't like the concept of a "byte-level" copy - unless you can guarantee similar architecture (and by implication, size).
Makes more sense to concentrate on data replication - stage4 seems to work o.k.

Gentree · Posted: Wed Jun 22, 2005 2:15 pm Post subject:

Yes , I agree.

I had a seagate 80 to copy to a seagate120 of the same family so it was pretty close.

It obviously left me with an 80G setup on the 120 but I just needed to use parted to increase the extended partition upwards and create new paritions to use the space.

I would not have wanted another 40 SeaGigs on the exisiting partitions anyway.

It is a bit of a hack so it has to be used with care but it is beautifully compared to duping all the partitions I had , formatting them , copying the contents and redoing my grub setup.

That simple command did the whole lot , perfectly.

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lemino · Posted: Thu Jun 23, 2005 2:46 pm Post subject:

I get what seems to be a nice cloon but it is a little slow at startup and it hangs when trying to stop fcron during shutdown. Otherwise it seems to be working alright. Ideas?

Gentree · Posted: Thu Jun 23, 2005 3:08 pm Post subject:

Does the old partition still work as before?

make a new line in grub.conf so you can boot one or the other and compare directly.

You could dig around out of curosity , but if it seems not be the same boot to a live CD and just do

cp -a src_partn dest_partn

no sense in messing around. It was supposed to save time!

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duderonomy · Guru Joined: 20 Mar 2004 Posts: 349 Location: SF Bay Area

bonbons · Apprentice Joined: 04 Sep 2004 Posts: 250

rutski89 · Posted: Thu Jun 23, 2005 5:55 pm Post subject:

I don't like the idea of byte copying for cloning and re-use another a new drive. Its perfectly fine for backing up a drive beforeing trying some seriously dangerous operations, but other than that I wouldn't trust it as more than a hack or quick fix; reinstalling will produce better results.
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duderonomy · Guru Joined: 20 Mar 2004 Posts: 349 Location: SF Bay Area

canal · Apprentice Joined: 28 Sep 2004 Posts: 203

rutski89

Corona688 · Veteran Joined: 10 Jan 2004 Posts: 1204

The way I generally do drive copies is:

EASYdoor · Posted: Sun Aug 21, 2005 1:41 pm Post subject: hi all

I can confirm that using the dd clone method works ONLY with EXACT geometry from the drive that u are cloning.
I tried to clone IBM 41.1 GB onto MAXTOR 40 GB....well everything went well and the "no space left on device" ....when i've manually mounted the drive every data that i needed was there.../boot /root ....everything but when i've restarted the system fschk found an error and i was foreced to do it manually which later on hang it self....so no good

i've figured it out that you can manually change CHS (Cylinder/Head/Sector) using fdisk (advanced options) or cfdisk.
Well if i do that i'll have to do an extra empty partition & mount to use it. I don't want that, so I'm currently backing up files with cp -aiv method. Now the question? Do i have to copy the mbr data or anything else to succsesfully boot my new system??

i did my own partitions, little different than the previous system /boot now 100M & swap 1G & /root everything else (200 GB seagate)
i've mounted /dev/hdh1 /b1 && /dev/hdg1 /b2 + root partition & copied everything with -aiv option. Do I have to do anything else?!??

like chroot & install grub???
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Kaapeli · Posted: Sun Aug 21, 2005 3:29 pm Post subject: Re: hi all

cybrjackle · Apprentice Joined: 09 Jan 2003 Posts: 248 Location: USA

EASYdoor · Posted: Sun Aug 21, 2005 6:11 pm Post subject:

cybrjackle · Apprentice Joined: 09 Jan 2003 Posts: 248 Location: USA

I just time everything, its a habbit