RE: How to clone to a smaller HDD without messing up partitions?

[Felix Ehlermann]

Hi Shahrukh,

You can just specify partitions (/dev/sda1) rather than the entire device 
(/dev/sda) without problems.
Of course this requires the partition table to be without damage.

I would recommend to
* always use a mapfile - it does never hurt, takes very little space and in 
very many cases you will be happy to not have omitted this.
* if possible use an file not a blockdevice as outfile

So rather than running
> ddrescue -f -n /dev/sda /dev/sdb
which has a lot of risks and implications (e.g. the destination drive should be 
zeroed first, etc.), I would go with the following command(assuming sda2 is the 
partition with your relevant data)
> ddrescue /dev/sda2 /media/my-usb-hd/sda2.img /media/my-usb-hd/sda2.map

Once you have finished recovery you can partition a healthy drive and then 
restore the image into the according partition with `ddrescue -f 
/media/my-usb-hd/sda2.img /dev/sdb2`.
If anything fails, you can retry from the image-file without risk of losing 
more data.
You can also run recovery tools on the image file (or rather a copy of it, in 
case the tool messes something up) to recover your data.


Kind Regards
Felix

P.S.

> lsblk version
> -------------
> sda             465.8G
>   -sda1 RECOVERY   9.8G ntfs
>   -sda1 OS        54.9G ntfs

Is this a typo or are there really two sda_1_ partitions on sda?


-----Original Message-----
From: Bug-ddrescue <bug-ddrescue-bounces+fehlermann=address@hidden> On Behalf 
Of Shahrukh Merchant
Sent: Samstag, 26. Oktober 2019 04:04
To: address@hidden
Subject: How to clone to a smaller HDD without messing up partitions?

I have a 500 GB HDD (source) that I want to clone to a 320 GB HDD 
(destination). Both are MBR. Only about 60 GB of the source drive is 
actually in use (in 2 partitions), the rest (400+ GB) is in unallocated 
space.

I will ask more specifically in two different ways:

1. I would like to tell ddrescue to clone the entire drive, i.e.,

ddrescue -f -n /dev/sda /dev/sdb

BUT with options that effectively say "and don't worry if you run out of 
space on the destination drive--just stop copying since the important 
stuff is at the start anyway." Can I do that, and how? (And other than 
relying on the Windows Disk Management visual to believe that the 
unallocated space is all at the end, which it seems to be, is there some 
other tool I can use to let me confirm that explicitly?)

2. If the answer to the above is "No" or "Not recommended," then I would 
have to do the clone partition by partition. There are two partitions on 
the source disk as follows:

lsblk version
-------------
sda             465.8G
  -sda1 RECOVERY   9.8G ntfs
  -sda1 OS        54.9G ntfs

Windows 7 Disk Management version
---------------------------------
Disk0 Basic/465.76 GB/Online
--------
9.77 GB
Healthy (Active, Recovery Partition)
--------
OS (C:)
54.93 GB (NTFS)
Healthy (Boot, Page File, Crash Dump, Primary Partition)
--------
401.07 GB
Unallocated
--------

So if I do the clone partition by partition, two things are not clear:

(a) What is the sequence of commands I need to use (and how to I prepare 
the destination drive in advance). Can I do, for example:
     ddrescue -f -n /dev/sda1 /dev/sdb
     ddrescue -f -n /dev/sda2 /dev/sdb
and have ddrescue figure out that I mean "put them in their 
corresponding places on the destination drive based on how it was on the 
source drive and fix the MFT so it does the right thing" (seems a lot to 
ask for, but maybe it does!)?

(b) How do I maintain the integrity of the destination drive w.r.t. the 
MFT of that drive being properly configured (since it is not part of the 
ddrescue copy, as I understand it, if I do a partition at a time), and 
in terms of the destination drive booting fine in exactly the same way?

Basically, the unallocated space at the end is the only part that I want 
to be different, owing to the different in drive sizes.

Thanks!

Shahrukh