Thread: How to mount a compressed backup HDD image (the tricky way)

few days ago tried restore single file compressed partition image file generated partimage. unfortunately had bad luck .once checked faqs on official website found out kind of backups useless. mean saying useless can backup , restore entire partition of hard drive cannot decompress, browse or mount archive , cannot restore single file/folder or group of files/folders. pity because of people perform kind of backup typically want able restore specific files later on.

so... here solution have found out , hope might there want mount backups , browse , restore single files seamlessly.

make sure have installed dd , squashfs

code:

sudo apt-get install coreutils  sudo apt-get install squashfs-tools

the backup file generated dd raw data , have same size source partition. if source partition 20 gb need minimum 20 gb of free space on destination drive want place backup. before start process, might want fill partition zeros. way save lot of space on final squashed backup file.

source partition have mounted in order generate zeroed file :
simplify sudo commands ,you may use

code:

sudo -s

switch terminal super user session don't need type sudo every time

code:

dd if=/dev/zero of=/media/yourpartition/big_file_full_of_zeros bs=1024

once done have delete it:

code:

rm /media/yourpartition/big_file_full_of_zeros

if need full hard disk backup (including of partitions)than have repeat same procedure each partition.once done have unmount source partitions , go.
if need full hard disk backup (including of partitions)than have same procedure each partition
need backup system or home partition cannot unmounted . in case boot cd-rom , perform backup

identify source partition , unmount it

code:

fdisk -l umount dev/sdx

start backup process

code:

dd if=/dev/sdx of=/media/your-destination-drive/ddbackp

when done have squash file.

code:

mksquashfs ddbackup /media/yourbackupdrive/squasheddd

when ready have mount squasheddd , ddbackup

first create mount points

code:

mkdir /mnt/squash mkdir /mnt/dd

code:

mount -t squashfs /media/drive/pathtofile/squasheddd /mnt/squash -o loop

need examine ddbackup file in /mnt/squash in order obtain necessary information determine superblock

code:

fdisk -lu /mnt/squash/ddbackup

offset = 512 x start block value (in case 63 ) = 32256
sudo mount -o loop,offset=32256 -t auto /mnt/squash /mnt/dd
open favorite file manager , browse , copy whatever need

thanks howto!
tried mount zipped files, , possible, takes time mount zipped image of 24g windows system partition.
used squashfs method, , ok @ beginning, squashed 24g image 16g squashfs file, while gzipped image 21g (but honest, hadn't created 0 files in free space of source partition before zipping).
when started mount squashed image, , looking proper offset, run accross strange info:

code:

ubuntu@ubuntu:~$ fdisk -lu /media/system.squash/system.ddbackup  must set cylinders. can functions menu.  disk /media/system.squash/system.ddbackup: 0 mb, 0 bytes 255 heads, 63 sectors/track, 0 cylinders, total 0 sectors units = sectors of 1 * 512 = 512 bytes disk identifier: 0x69205244  doesn't partition table selected wrong device.                                 device boot      start         end      blocks   id  system /media/system.squash/system.ddbackup1   ?   218129509  1920119918   850995205   72  unknown partition 1 has different physical/logical beginnings (non-linux?):      phys=(368, 111, 45) logical=(13577, 238, 11) partition 1 has different physical/logical endings:      phys=(371, 101, 51) logical=(119521, 238, 60) partition 1 not end on cylinder boundary.

as described here, calculated offset 512x218129509=111682308608 , tried mount:

code:

ubuntu@ubuntu:~$ sudo mount -o loop,offset=111682308608 -t auto /media/system.squash/system.ddbackup /media/system.image mount: must specify filesystem type

ok, said ntfs:

code:

ubuntu@ubuntu:~$ sudo mount -o loop,offset=111682308608 -t ntfs /media/system.squash/system.ddbackup /media/system.image ntfs signature missing. failed mount '/dev/loop2': invalid argument device '/dev/loop2' doesn't seem have valid ntfs. maybe wrong device used? or whole disk instead of partition (e.g. /dev/sda, not /dev/sda1)? or other way around?

well. gave , tried mount without offsets, , got result:

code:

ubuntu@ubuntu:~$ sudo mount -o loop -t auto /media/system.squash/system.ddbackup /media/system.image

and works! mounted original partition, , looks same.

code:

ubuntu@ubuntu:~$ df -h filesystem            size  used avail use% mounted on /dev/loop1             16g   16g     0 100% /media/system.squash /dev/loop2             30g   24g  6.2g  80% /media/system.image /dev/sdb1              30g   24g  6.2g  80% /media/system

there files in mounted image squashed file:

code:

ubuntu@ubuntu:~$ ls -l /media/system.image/ total 129084 -rwxrwxrwx 1 root root        60 2010-04-10 19:26 autoexec.bat -rwxrwxrwx 1 root root       292 2007-06-06 21:13 boot.ini -rwxrwxrwx 1 root root    259776 2005-07-13 23:06 cmldr drwxrwxrwx 1 root root      4096 2008-07-29 13:52 documents , settings -rwxrwxrwx 1 root root     47564 2004-08-03 20:38 ntdetect.com -rwxrwxrwx 1 root root    250032 2010-06-06 19:39 ntldr drwxrwxrwx 1 root root     24576 2010-06-06 20:21 program files drwxrwxrwx 1 root root      4096 2009-04-26 09:56 recycler drwxrwxrwx 1 root root      4096 2010-02-20 09:53 system volume information drwxrwxrwx 1 root root     45056 2010-06-26 10:36 windows

and diff showed no difference (well took time):

code:

ubuntu@ubuntu:~$ diff -r /media/system/ /media/system.image/ ubuntu@ubuntu:~$

so, reason of this? why need no offset mount squashed image?
in original partition table source partition starts sector 1, maybe reason:

code:

disk /dev/sdb: 164.7 gb, 164696555520 bytes 255 heads, 63 sectors/track, 20023 cylinders units = cylinders of 16065 * 512 = 8225280 bytes disk identifier: 0x23172316     device boot      start         end      blocks   id  system /dev/sdb1   *           1        3833    30788541    7  hpfs/ntfs /dev/sdb2            3834       20023   130046175    5  extended /dev/sdb5            3834       20023   130046143+   7  hpfs/ntfs

but know exactly, why? pls explain this?

also, mounted image appeared read-only, same mounting of zip files... squashed file mounted more faster zipped one, , big advantage.

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