Copy vs. Clone -- what's the difference?

Started Jun 10, 2012 | Discussions
PicOne
PicOne Veteran Member • Posts: 6,932
Copy vs. Clone -- what's the difference?

Assuming I want to copy all of the data on an old drive (data drive, not OS/Apps) onto a new drive. Is there any difference and/or advantage/disadvantage to using "Clone" function from eg. Easeus Todo, vs. just a drag/copy of the old drive folder to the new drive?

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Bob Collette Veteran Member • Posts: 3,842
Re: Copy vs. Clone -- what's the difference?

If the files are just data files (documents, pictures, etc.) there isn't any need to clone the drive, a simple copy will do. However, if you're trying to copy a drive that has an operating system on it (some version of Windows) and you want the copied drive to be able to boot up, then you need to clone the drive. There are a number of hidden files along with the MBR (Master Boot Record) that need to be copied over for the new (copied) drive to be able to boot.

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Jim Cockfield Forum Pro • Posts: 16,342
Re: Copy vs. Clone -- what's the difference?

PicOne wrote:

Assuming I want to copy all of the data on an old drive (data drive, not OS/Apps) onto a new drive. Is there any difference and/or advantage/disadvantage to using "Clone" function from eg. Easeus Todo, vs. just a drag/copy of the old drive folder to the new drive?

Usually, good cloning software is going to make an exact sector by sector copy of a drive. So, everything on the drive you're cloning to will be identical to the source drive.

That would include any file fragmentation, locations on files on the drives, etc.

When you copy the files, they may end up in a different order than they were on the original drive.

Personally, if I wanted to move everything to a new drive that was used for data file purposes, I'd probably just clone it.

That way, the drive heads are not having to move back and forth between the file locations and the MFT (Master File Table), assuming it's NTFS; or FAT (File Allocation Table) if it's FAT IOW, the OS would need to move back and forth between the indexing system and any physical locations the files are located in on the source drive; and between the MFT and file locations it's writing them to on the destination drive.

Instead, most cloning software is just going to read the sectors on the source drive, one right after the other, then write to the same sectors on the destination drive.

There are pros and cons to both approaches. For example, a copy versus clone may inherit the permissions of the user on the OS making the copy (that can be good or bad), which may be different than the were if the source drive came from a different OS install.

With a copy versus clone, physical file locations may be in different places on the destination drive, too (which may be a good thing, or a bad thing, depending on where the files were located on the source drive and if they were fragmented or not).

But, if I'm trying to duplicate an old drive to a new one, I usually just clone it. I use a linux utiility called ddrescue for that purpose, since it can also work around any sector errors on the source drive. For example, this command would copy from the first drive in the system to the second drive in the system, making an exact sector by sector copy of it, regardless of file system:

ddrescue dev/sda dev/sdb

But, there are a number of Windows based tools designed for cloning drives you could use.

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JimC

joey_B
joey_B Veteran Member • Posts: 3,080
Re: Copy vs. Clone -- what's the difference?

Copying is done to files, and it alters the datestamp and permissions on the resulting file. Cloning is done to parts of harddrives, and it makes a 1 on 1 copy of that part of the drive. Both have their advantages, depending on what you want to do with the result.

PicOne
OP PicOne Veteran Member • Posts: 6,932
Re: Copy vs. Clone -- what's the difference?

Basically, I'm just getting a new computer, and was going to use a SATA-USB housing to move/copy my data drive from the old PC (500gb internal) to the new computer's internal disc (2tb). Wasn't sure if I should just drag n'copy thru Windows Explorer, or bother getting/using eg Easeus Todo and use the 'clone' function?

My first impression was that a clone would inherently bring over all fragmentation (and any other kinds of garbage) that may now exist on the old (5-6 yrs data drive), while a copy would not. I hadn't considered though the timestamp issue, but with photos at least, and using Lightroom, I don't think (?) would be a problem relinking the new location of photos with my catalog.

joey_B wrote:

Copying is done to files, and it alters the datestamp and permissions on the resulting file. Cloning is done to parts of harddrives, and it makes a 1 on 1 copy of that part of the drive. Both have their advantages, depending on what you want to do with the result.

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Jim Cockfield Forum Pro • Posts: 16,342
defrag it later. ;-)

PicOne wrote:

My first impression was that a clone would inherently bring over all fragmentation (and any other kinds of garbage) that may now exist on the old (5-6 yrs data drive), while a copy would not.

Clone it, and if you see files you don't want anymore, just remove them after you clone it. That way, you're not going to miss anything by accident (or because Windows Explorer didn't deal with some files or folders properly, which does happen from time to time) and you'll retain all of the original file attributes.

Then, after you've cloned it and remove any files you don't want anymore, defrag it for faster performance:

http://windows.microsoft.com/en-us/windows7/improve-performance-by-defragmenting-your-hard-disk

If you prefer to copy the files, you may want to consider robocopy. It can do things like retain the original file attributes. More about it here:

http://en.wikipedia.org/wiki/Robocopy

Or, look at something like richcopy instead. See more about it here:

http://technet.microsoft.com/en-us/magazine/2009.04.utilityspotlight.aspx

But, if you use it's multi-threaded mode, you're still going to want to defrag the drive later (as from what I understand, files may be fragmented on the destination drive that way).

Personally, I'd just clone the drive. That way, you're not going to miss anything by accident or because something in the utility you're using (Windows Explorer, robocopy, richcopy, etc.) didn't handle the copying properly due to something odd (characters in file naming, directory path length, etc.).

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JimC

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