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Disk imaging and cloning

Disc imaging & cloning

What is disk imaging / disk cloning ?

Disk imaging or cloning is the process of copying the entire hard disk contents. Whilst this means 'everything' is copied, it also means that the data can only be 'restored' to the same size disk (or disk partition**) as the original.

'Cloning' was originally used to describe software that made an exact 1:1** copy of the disk surface, direct from one disk to another.Software that could copy the contents*** of a (single) partition to a 'backup' or 'image' file used the term 'imaging'.However, these days the terms have become almost interchangeable - newer versions of cloning software are able to create file 'images', whilst most imaging software can now 'clone' direct from one disk to another

**Exact 1:1 means 'ignoring the directory' and copying the entire formatted disk surface. Whilst this will capture the MBR, any 'hidden' partitions and both 'deleted' and 'unused' sectors, it will typically exclude any sectors marked 'bad'.

Early 'copy protection' systems would sometimes 'hide' encryption 'keys' in 'bad sectors' to prevent the use of 'cloning' to copy games. Whist this is not longer used on hard disks it is still quite a popular trick on some CD/DVD games (and some movie DVD's)

***Imaging software that copies the contents of a disk partition has to rely on the directory to find the files. Deleted files are typically skipped.If your directory becomes corrupted (quite possible on those useless FAT32 formatted USB connected 'Backup' drives) your imaging software will typically continue without complaining (and generate '0 byte' entries for any corrupted file) and may even claim to have 'Completed OK'.

If you clone the entire disk, you (should) get all the partitions, including any 'hidden' ('factory restore') partition. Typically, disk imaging and cloning software is unable to copy the disk (or partition) it is running from, so you have to boot it from a 'Live CD'. Specific limitations are discussed below

Most imaging software will refuse to 'restore' to a partition smaller than the original (i.e. even if you used 100Mb of a 1Tb partition you are still limited to restoring that 100Mb to a 1Tb (or larger) partition). For this reason, it's a 'good idea' to use Drive Partitioning software (such as GParted Live) to reduce the size of your partition before creating an image.

Note that disk imaging & cloning is NOT a 'substitute' for making back-ups of your files.

First, imaging a 'typical' 2Tb hard disk is going to take hours (if not days), second few of us have enough storage space to 'save' more than one or two 2Tb 'images', and finally you can (generally) only 'restore' the entire 'image' = so having to wipe your entire C: disk in order to get back a single word document you accidentally deleted is perhaps not the best solution :-)

Imaging and cloning are a way to move from an existing C: system drive that you have 'outgrown' to a new, much larger, driveNote that you can't run two computers on the same network with the exact same 'image' - their 'identities' (SID's and GUID's) will 'clash' - Corporations who to 'roll out' disk 'images' to multiple PC's use special 'SID walker' software to 'customise' the Identity of each one

What are the limitations of DriveImage XML ?

DriveImage XML is not Open Source, but is free for personal use.

The 'image' file format used is based on XML, so unlike most other 'images', the contents can be 'browsed' and accessed by 3rd party tools.

Unlike many other imaging software applications, DriveImage is also able to copy the system disk it is running from !

It uses Windows own 'backup' Services ("MS Software Shadow Copy Provider" and "Volume Shadow Copy" (VSS), both of which need "Remote Procedure Call (RPC)") to image a running system. If these services are 'disabled', DriveImage will fail with 'VSS Error'.

One drawback is that DriveImage is unusable if your C: system disk has become corrupted (and won't boot). Further, it is unable to copy 'corrupted' files.

It is possible to create a 'Live (Windows) CD', however MS Licence restrictions mean you have to do that yourself. DriveImage would need to be 'slipstreamed' onto a bootable Windows XP CD (see my SETI-Wall how to boot from CF/USB page or see here).

DriveImage 'Good compression' is about 4x slower than 'Fast compression' & should be avoided if your drive contains more than 20Gb of data.

DriveImage takes approx 1hr per 100Gb of actual* data using fast compression (* 'unused' parts of the disk are ignored).

DriveImage can only restore to a partition that is the same size (or larger) than the original, regardless of the actual data size i.e. regardless of the amount of disk space actually used.

This is highly annoying since it means an image file of (say) a few hundred Mb, being the contends a 2Tb disk, can only be restored to another 2Tb (or larger) disk !

DriveImage does not support direct disk to disk 'clone', nor can you save (or restore) an image to the 'source' drive. However it's image 'file' based approach does mean you can save to & restore from a simple network (mapped drive) 'share'

Using a 'share' makes it possible to directly replace a Laptop C: drive you are 'outgrowing' with a much larger drive, however note below re: 'System Restore' partition

Drive Image does not save & restore anything 'outside' the file system (so it won't 'see' a hidden partition or the MBR (Master Boot Record)). This means a bootable drive image taken from C: and 'restored' to D: probably won't boot (even after you make D: the new C:) unles D: was bootable** BEFORE you 'restore' to it.

To ensure D: will boot after 'restoring' an image from C:, in DriveImage (running on C:), select Tools, 'Set new Disk ID', and then follow the instructions.

** To be bootable, the C: image has to be restored to first partition on a drive, which must be a "primary" partition and have been made "active" (i.e. have an MBR). Windows will boot from the first drive (DISK0) detected by the BIOS, so to boot from D: (rather than your existing C:), swap the C: & D: drive cables.

What are the limitations of Clonezilla ?

Clonezilla is Open Source and is provided as a bootable ('Live') Linux CD or bootable USB stick.

Whilst it can be run under Windows, it can't 'image' a running system.

Clonezilla can 'clone' from one disk direct to another disk or create an 'image' of the (entire) disk which can be saved to local storage (i.e. another hard disk or a USB stick, including the one it booted from) or to a network FTP Server.

Clonezilla images are not directly 'browsable' or accessible, however the major advantage of Clonezilla is that it 'clones' (copies & restores) everything, including any 'corrupted' files / directories, any hidden (factory restore) partition and (of course) the MBR.

A cloned disk is indistinguishable from the original, which is ideal when the disk has become corrupted (since you should always make a copy before trying to recover anything) and ESPECIALLY when setting up a RAID (mirror).

What are the limitations of PING (Partimage Is Not Ghost) ?

PING is Open Source and is provided as one of the file & system 'recovery' utilities on the bootable Freeware SystemRescueCD 'Live CD' (it can also be added to a 'Bart's PE' bootable XP CD).

It can also be found on a 'minimalist' Linux here, although you must provide your email address to obtain the download.

As with most other cloning software, it is not able to 'image' a running system. It also only 'images' actual files (i.e. the 'used' part of the disk drive)

NTFS is 'not fully' supported - specifically, it can't copy 'compressed' or 'encrypted' folders and has some limitations when it comes to 'finding files' on a 'fragmented' disk.

So, before trying to 'save' an NTFS disk, ensure no folders are set to 'compressed' (or encrypted). Since PING only saves 'used' parts of a drive, it has to 'skip over' unused space - and it's limited ability to 'trace' file fragments beyond 'empty' space' means you should run a 'Defrag' on any disk first (you will get an error message if the files are too fragmented (or compressed) or corrupted)).

If the image 'saves' OK, it will 'restore' OK, but like many others, it will refuse to 'restore' to a partition smaller than the original (so if your 'image' is 100Gb from a 1Tb drive, it can only be 'restored' to 1Tb (or larger) drive).

This means it can't be used to 'shrink' partitions, however high capacity drives are so cheap it's unlikely this limitation will ever be of any concern

What are the limitations of g4u (ghost 4 unix) ?

This app. can only image to & from a FTP Server. Unless you have a Home Server / NAS (with FTP capability enabled), don't bother with g4u.

It's one real advantage is that it's small enough to run from a bootable floppy disc !

This means it can be used to 'rescue' data from ancient non-booting Laptop without a CD/DVD (or USB boot capability) but with a built in (or external connected**) floppy disk !

** Chances are you will need to 'track down' the 16bit 'DOS Drivers' for your laptops floppy and it's network interface so g4u can access them

What are the limitations of EaseUS ToDo Backup free ?

Free for personal use, I have used this application a number of times to upgrade laptop hard drives via a network 'share' (image copy), as well performing a local drive 'clone'

During install, it will offer to create a 'default' folder for your backup 'images' on a second (or 3rd) hard drive. It can't 'save' to the same physical drive as the system (C:), however it can use a network 'share'

It also asks you to 'Join the customer Experience Improvement program' = needless to say this is simply a way to 'harvest' your email address and spam you with 'special offers' and other junk adverts - so 'just say no' :-)

When launched, it will connect to the Internet (presumably to check for updates, so you can 'OK that) and then tries to install 5 'start up' components (EuWatch.exe, 2 'tray' tasks, 'Agent.exe' and 'Guard Agent.exe'). None of this garbage is of any use unless you expect to run a back-up (or clone) every time you boot (highly unlikely) = so 'just say no'

It supports both 'disc clone' and 'partition copy', and, unlike many other applications, is quite capable of cloning your 'live' system C: partition (and without trying to use the MS 'Volume Shadow Copy' service)

One drawback is that whilst it can image a (running) system (C:) partition to a network 'share' just fine, it is extremely slow (approx 2Gb per hour). However I successfully used it to create a 'backup image' of an almost full 60Gb laptop drive (it took just under 30 hours !).

Restore was rather faster - 'restoring' the 60Gb 'image' to a new 500Gb SSD drive (that I temporarily housed in the Sever i.e. same computer as the back-up image) took less than 20 mins. !! On installing the new drive in the laptop, it 'booted' straight away without any problem.

However on cloning direct from a 750Gb C: drive to a local installed D: drive it took just over 60 hours (so about 12Gb per hour) - and then 'locked up' in 'create drive letter' when it reached the unused space at the end of the drive. Whilst this may have been much faster than 'network share' imaging, it is still somewhat slower than might be expected.

It did correctly copy the MBR, the 'hidden' (factory restore) partition and the main (C:) partition. Initially the 'cloned' drive booted straight away without problem, however it soon started 'locking up' in the middle of file copies / drag 'n drops. After half a dozen forced power cycles I started to get 'Registry had to be restored from back-up or log-file' warnings after logging-in and then it started to lock up at the initial 'user log-in' (choose your user account) page

Booting from an other drove and running Microsoft 'Check Disk' tool resulted in 'Unable to complete check' near the end of the second pass. I thus concluded that the 'clone' had actually failed ...

It's a bit of a mystery why EaseUs is so slow at 'cloning' (at approx 0.2 Gb/min) but can 'restore' is at least 15x faster (at approx 3 Gb/min).

If you have to use EaseUs, I recommend you use it ONLY for the 'system' (C:) partition - all other partitions can be 'copied' 10 to 20 times faster using Windows itself :-)

In conclusion, whilst EaseUs is about the only way for those with older laptops without a CD/DVD drive (or USB boot support) to replace their hard drives, it's just too slow for 'general' use.

Free File Sync 6.7 (Open Source)

Not really intended as an 'imaging' tool, this utility can, however, 'mirror' the contents of any folder (or drive) to any other chosen folder (or drive). It is at least 2x faster than using Windwos Explorer 'drag and drop' and is especially fast at copying to and from network 'shares'. It uses VSS to copy 'locked' (system) files.

The 'Update' (rather than Mirror) mode allows new files on the source added to the destination and older dated files to be replaced with newer ones (files and folders of different name on the destination are ignored, which can be a problem, see below). You can, of cousre, view what it intends to do (create / replace / delete) and 'deselect' on a file by file basis before letting it go ahead with the rest

FreeFileSync is how I keep my Laptop and Desktop work 'in step' whlst automatically creating a backup (via my Server) every time I do an Update (or Mirror). The only drawback is when you rename a file/folder on your 'source' = the rename is not 'spotted' as such (it's seen as a new file/folder) and an 'Update' (rarther than a Mirror) will result in both old and new files/folders existing on the destination

The current version (7.2, July 2015) also runs on Android tablets

To see how 'scripts' can help protect your data, click "Next>>" in the navigation bar left

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