Best Way To Clone Large Drive To Smaller Drive

Brad McAfee
Brad McAfee used Ask the Experts™
We have done this over the years with a variety of different software but wanted to get some feedback from you experts.

What is the best commercial and/or open source software (that is user friendly) to clone a larger drive (example: 1TB SSD) to a smaller drive (example: 480GB SSD)?

(If it matters they are Windows OS drives.)
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David FavorFractional CTO
Distinguished Expert 2018

So long as the data will fit you can use xcopy or Robocopy or any other copy utility.

If the data won't fit + you still must have this operation complete successfully, you'll have to compress files in place, either by directory or by file.

Using zip might work. If data still won't fit, use zstd which compresses much further than zip, in roughly the same amount of time.

For example, here's a sample run of zstd...

# file count to compress
find dclsites -type f | wc -l

# size of data to compress
du -hs dclsites
105G	dclsites

# create a zstd tarball
time nice -19 tar -I "zstd --threads=0 --no-check -19 --long=31" -cf 2018-06-28-dclsites.tar.zst dclsites

real	341m2.588s
user	751m59.666s
sys	8m13.122s

# size of resulting tarball
ls -l
total 63G
drwx--x--x. 51 root root 4.0K Jun 28  2018 dclsites/
-rw-r--r--   1 root root  63G Mar 31 01:29 2018-06-28-dclsites.tar.zst

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In your case, you'd like compress the file on the big disk first, then copy over the compressed file, rather than creating a tarball/archive.

Hi David,

Great post - and good example of using zstd, but I don't believe you can just xcopy / robocopy / rsync etc one drive to the other, as it won't take over the MBR / GPT etc.

For me, I would normally try to compress the source drive (data) as per David's suggestion, then shrink the drive partition(s) such that they are smaller (preferably) than the destination drive, then clone / image them over.

If you are looking for something with a GUI, then CloneZilla can be told to ignore drive size issues, and do an image / clone regardless.

In Clonezilla, go to 'expert / advanced mode', and tell Clonezilla to ignore the destination disk size while restoring by selecting the 'icds' option:

David FavorFractional CTO
Distinguished Expert 2018

Alan is correct. I hadn't thought about cloning so the new drive was bootable, because normally in this case you'd use exactly the same drive size or bigger.

If you must do this, take Alan's suggestion + give Clonezilla a drive.
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Fellow 2017
Most Valuable Expert 2018
Hi Brad,
If it matters they are Windows OS drives.
Yes, it matters.

I use Casper to clone Windows drives:

I have used it many, many times in recent years to clone to a new SSD. I even run it every evening in the wee hours (it utilizes the Windows Task Scheduler to schedule jobs) on several machines to clone the hard drives (a mix of HDD, SSD, and hybrid). It has an intelligent cloning mechanism so that it copies only the necessary tracks. The first run takes a while, but after that, it's extremely fast. It can clone to the same size drive or to a larger one or even to a smaller one, as long as there is enough space on the smaller one to house the used (non-free) space from the larger one. It's not free, but it's reasonably priced and worth every penny.

Two other well-regarded (also commercial) products are Acronis and Macrium:

I used Acronis previously, but now prefer Casper.

On the free and/or open source front, I've heard good things here at EE about these (some may be free only for non-commercial use — check the licensing terms for each):

AOMEI Backupper Standard FREE
DriveImage XML
EaseUS Disk Copy Home
Paragon Backup&Recovery Free

Also, some of the free ones may not be able to clone to a different size drive (either bigger or smaller) and may not support Windows 10 — you'll need to check the specs for each, as I haven't tried any of them myself, because I do all of my cloning now with Casper (which has always been successful for me). Here's a 5-minute EE video Micro Tutorial, Cloning a Hard Drive with Casper, showing how to do it:

As a disclaimer, I want to emphasize that I have no affiliation with this company and no financial interest in it whatsoever. I am simply a happy user/customer. Regards, Joe
Distinguished Expert 2017

Depending on which SSDs  (manufacturers are involved)
so long as the amount of data on the 1Tb is less than the 450Gb that is likely the usable space on the 480SSD.
Presumably you do not want to have 0 free space..

Each vendor provides cloning tools and most of them will auto downsize the partition size on the new SSD provided the amount of data on the existing drive fits within the confines of the new one.
All using the autmatic will downshift the large partition from letsay 950GB to 450GB
The EFI if any, MBR paritions will remain at their existing sizes
100-500 MB

Acronis for either SSD, (WD/sandisk, micron, etc.)
Disk Magician for samsung
Seadiscwizard (acronis version for seagate drives)

You need to pick one either for the one that exists in the system or based on the one you are adding.

Have not used, but casper should do the trick as Joe pointed out.
Top Expert 2013

well for cloning to smaller drives - i suggest to clean out the Original disk first from not needed data, and software., to get a smaller Original drive.
i use the Paragon software, mentioned by Joe, and it does a good job on cloning to smaller drives.
as for the best way - there is none imo; you measure up the situation each time, and correct it as needed.
using zip may seem a solution, but it adds 2 operations to the workload : zip + unzip, so i' won't use that
I've used and attempted to use most, if not all of these at one time or another. Casper rocks, I've yet to find one it doesn't handle, unless the drive to be replaced has too many errors, and then nothing will work.
Joe nailed it.

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