Cloning a HD vs. Copying Files - Which is faster?

Question

Which is faster if I wanted to copy all files on a 6 TB hard drive to an 8 TB external hard drive? Cloning the 6 TB hard drive with Macrium Reflect or copying all files with UltraCopier? I noticed that UltraCopier will take me 48 hours to copy all files. But how long will it take to do the same task with cloning?

Solution 1

Cloning will be much. much faster. I cant say how much, as it will depend on the speed of your setup. However, it shouldnt take more than a few hours.

Copying has to open a file, read it, write it, and then close it. Virus scanners will look at every file you open, as well. Other file system based hooks could slow it down, like indexing.

Cloning simply reads and writes bits. Nothing will slow it down other than disk usage.

Solution 2

In my experience, it has always been faster to copy all the files from one drive to another than to clone the drive. In theory, it will should be faster to copy files than to clone the drive because when cloning, you must read and write every block on the drive, even the empty ones, whereas with copying you only read and write the data.

Since you are referring to 6TB and 8TB drives, I assume you are probably using them as storage and not boot drives, which means you can just copy the files because preserving the MBR and/or partition table is not important.

Edit: If the disk is basically full, then cloning would probably be the better bet since there is less overhead involved, as Keltari pointed out.

Solution 3

Something the others answers didn’t address is fragmentation.  If a disk (by which I mean a file system) has been very active (i.e., files being deleted; files being modified over a period of days) and has gotten very full, then it is likely to have become fragmented.  That means that the blocks of a file are not necessarily close to each other on the disk.

This, interestingly, has two opposite consequences:

• Copying the files typically means copying the files one at a time, sequentially.  (A copy program might be multi-threaded, and process multiple files in parallel, but I don’t see why it would.)  Copying a fragmented file may require a lot of physical seeking (i.e., moving the I/O head(s) to different locations on the disk).  Thus, copying the files could take more time than copying the whole disk (which, generally, will be able to traverse the disk sequentially). 

• As stated above, reading a fragmented file is slower than reading an unfragmented file — that’s why we have disk defragmentation software.  If your disk has become fragmented, you may have noticed that disk I/O is slower than it was when the disk was new and empty.  Copying the whole disk will preserve the fragmented nature of the file system, and so the new disk will also operate slower than it is capable of operating (unless you defragment it as a separate step, and that will be very time-consuming).  Copying the files will automatically defragment the file system.

  So, while copying the files may take more time than copying the whole disk, you can look at the time as an investment that will pay off in faster I/O for months or years to come.

Note that all of the above refers to hard disks.  Fragmentation isn’t an issue with SSDs, because you can read blocks without any latency based on the distance between the blocks.

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Note: I did a Google search for “ultracopier”, and, on the first page of results, I found Ultracopier is used to mine cryptocurrency without the user’s knowledge · Issue #23 at GitHub, which, as the title suggests, claims that Ultracopier is (or was at one time) malware.

Comments

[sawdust]

The fastest method depends on the number of files and percentage of disk that is used. There is no answer that fits all circumstances.

[Keltari]

he said it would take 48 hours to copy. that means there are a lot of files. and there are different types of cloning, you do not have to read the entire disk

[Blaine]

...why does your answer exactly contridict keltari's

[sawdust]

"Cloning will be much. much faster." -- This answer is obviously false for a sparsely-populated disk. The cloning would mostly be copying unused sectors, which is a waste of time.

[Keltari]

@sawdust this answer is obviously true, as not all cloning tools require copying of unused sectors.