ntfsclone will efficiently clone (copy, save, backup, restore) or rescue an NTFS filesystem to a sparse file, image, device (partition) or standard output. It works at disk sector level and copies only the used data. Unused disk space becomes zero (cloning to sparse file), encoded with control codes (saving in special image format), left unchanged (cloning to a disk/partition) or filled with zeros (cloning to standard output).
ntfsclone can be useful to make backups, an exact snapshot of an NTFS filesystem and restore it later on, or for developers to test NTFS read/write functionality, troubleshoot/investigate users' issues using the clone without the risk of destroying the original filesystem.
The clone, if not using the special image format, is an exact copy of the original NTFS filesystem from sector to sector thus it can be also mounted just like the original NTFS filesystem. For example if you clone to a file and the kernel has loopback device and NTFS support then the file can be mounted as
mount -t ntfs -o loop ntfsclone.img /mnt/ntfsclone
If you want to copy, move or restore a system or boot partition to another computer, or to a different disk or partition (e.g. hda1->hda2, hda1->hdb1 or to a different disk sector offset) then you will need to take extra care.
Usually, Windows will not be able to boot, unless you copy, move or restore NTFS to the same partition which starts at the same sector on the same type of disk having the same BIOS legacy cylinder setting as the original partition and disk had.
The ntfsclone utility guarantees to make an exact copy of NTFS but it won't deal with booting issues. This is by design: ntfsclone is a filesystem, not system utility. Its aim is only NTFS cloning, not Windows cloning. Hereby ntfsclone can be used as a very fast and reliable build block for Windows cloning but itself it's not enough.
A file is sparse if it has unallocated blocks (holes). The reported size of such files are always higher than the disk space consumed by them. The du
command can tell the real disk space used by a sparse file. The holes are always read as zeros. All major Linux filesystem like, ext2, ext3, reiserfs, Reiser4, JFS and XFS, supports sparse files but for example the ISO 9600 CD-ROM filesystem doesn't.
Handling Large Sparse Files
As of today Linux provides inadequate support for managing (tar, cp, gzip, gunzip, bzip2, bunzip2, cat, etc) large sparse files. The only main Linux filesystem having support for efficient sparse file handling is XFS by the XFS_IOC_GETBMAPX ioctl
However none of the common utilities supports it. This means when you tar, cp, gzip, bzip2, etc a large sparse file they will always read the entire file, even if you use the "sparse support" options.
bzip2(1) compresses large sparse files much better than gzip(1) but it does so also much slower. Moreover neither of them handles large sparse files efficiently during uncompression from disk space usage point of view.
At present the most efficient way, both speed and space-wise, to compress and uncompress large sparse files by common tools would be using tar(1) with the options -S (handle sparse files "efficiently") and -j (filter the archive through bzip2). Although tar still reads and analyses the entire file, it doesn't pass on the large data blocks having only zeros to filters and it also avoids writing large amount of zeros to the disk needlessly. But since tar can't create an archive from the standard input, you can't do this in-place by just reading ntfsclone standard output. Even more sadly, using the -S option results serious data loss since the end of 2004 and the GNU tar maintainers didn't release fixed versions until the present day.
The Special Image Format
It's also possible, actually it's recommended, to save an NTFS filesystem to a special image format. Instead of representing unallocated blocks as holes, they are encoded using control codes. Thus, the image saves space without requiring sparse file support. The image format is ideal for streaming filesystem images over the network and similar, and can be used as a replacement for Ghost or Partition Image if it is combined with other tools. The downside is that you can't mount the image directly, you need to restore it first.
To save an image using the special image format, use the -s or the --save-image option. To restore an image, use the -r or the --restore-image option. Note that you can restore images from standard input by using '-' as the SOURCE file.
One of the features of ntfsclone
is that, it can also save only the NTFS metadata using the option -m
and the clone still will be mountable. In this case all non-metadata file content will be lost and reading them back will result always zeros.
The metadata-only image can be compressed very well, usually to not more than 1-8 MB thus it's easy to transfer for investigation, troubleshooting.
In this mode of ntfsclone, NONE of the user's data is saved, including the resident user's data embedded into metadata. All is filled with zeros. Moreover all the file timestamps, deleted and unused spaces inside the metadata are filled with zeros. Thus this mode is inappropriate for example for forensic analyses. This mode may be combined with --save-image to create a special image format file instead of a sparse file.
Please note, filenames are not wiped out. They might contain sensitive information, so think twice before sending such an image to anybody.
Clone NTFS on /dev/hda1 to /dev/hdc1:
ntfsclone --overwrite /dev/hdc1 /dev/hda1
Save an NTFS to a file in the special image format:
ntfsclone --save-image --output backup.img /dev/hda1
Restore an NTFS from a special image file to its original partition:
ntfsclone --restore-image --overwrite /dev/hda1 backup.img
Save an NTFS into a compressed image file:
ntfsclone --save-image -o - /dev/hda1 | gzip -c > backup.img.gz
Restore an NTFS volume from a compressed image file:
gunzip -c backup.img.gz | \\ ntfsclone --restore-image --overwrite /dev/hda1 -
Backup an NTFS volume to a remote host, using ssh. Please note, that ssh may ask for a password!
ntfsclone --save-image --output - /dev/hda1 | \\ gzip -c | ssh host 'cat > backup.img.gz'
Restore an NTFS volume from a remote host via ssh. Please note, that ssh may ask for a password!
ssh host 'cat backup.img.gz' | gunzip -c | \\ ntfsclone --restore-image --overwrite /dev/hda1 -
Stream an image file from a web server and restore it to a partition:
wget -qO - http://server/backup.img | \\ ntfsclone --restore-image --overwrite /dev/hda1 -
Clone an NTFS volume to a non-existent file:
ntfsclone --output ntfs-clone.img /dev/hda1
Pack NTFS metadata for NTFS experts. Please note that bzip2 runs very long but results usually at least 10 times smaller archives than gzip on a sparse file.
ntfsclone --metadata --output ntfsmeta.img /dev/hda1 bzip2 ntfsmeta.img
Or, outputting to a compressed image : ntfsclone -mst --output - /dev/hda1 | bzip2 > ntfsmeta.bz2
Unpacking NTFS metadata into a sparse file:
bunzip2 -c ntfsmeta.img.bz2 | \\ cp --sparse=always /proc/self/fd/0 ntfsmeta.img