Create image from unallocated hdd

Mahmoud Sobeih

8/18/24, 12:04 PM

I want to create file.img from unallocated hdd to another hdd ( backup the hdd ) to rescue my partitions and files in it . When I

dd if=/dev/sda of=dev/sdb/file.img

It shows

dd: failed to open '/dev/sda': permission is denied

Please help Can i create image from used space only on unallocated hdd this is all what i need . Because i will attempt to perform tdisk after creating the image to try rescue the partitions with files in it Recover data on a hard-drive that changed partition table

1 + 3

partitioning

gparted

hard-drive

external-hdd

guiverc

8/18/24, 12:12 PM

You've not provided any Ubuntu product/release details; but a normal system requires *elevated* privileges to copy devices, thus a "*permission denied*" error is usually indicative of the user not elevating privileges (ie. using `sudo`).

Bodo

8/18/24, 12:15 PM

You need `sudo dd ...` to access block devices. Make sure no partition of the disk is mounted while you copy the data. The destination file name `dev/sdb/file.img` looks strange. Have you mounted a whole disk (not a partition) to `dev/sdb/` in the current working directory? Special disk backup tools (e.g. clonezilla or partimage) might be better than `dd`.

Mahmoud Sobeih

8/18/24, 12:34 PM

Can i create image from used space only on unallocated hdd this is all what i need . Because i will attempt to perform tdisk after creating the image to try rescue the partitions with files in it https://askubuntu.com/q/1482115/1721749

Score:1

Ubuntu

Hannu

8/18/24, 3:40 PM

Please use lsblk and ponder on the data it displays.

Example:

$ lsblk -ape7 -o+FSTYPE
NAME             MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT FSTYPE
/dev/sda           8:0    0  7.3T  0 disk            
└─/dev/sda1        8:1    0  7.3T  0 part            ext4
/dev/nvme0n1     259:0    0  3.7T  0 disk            
├─/dev/nvme0n1p1 259:1    0  487M  0 part /boot/efi  vfat
├─/dev/nvme0n1p2 259:2    0   16G  0 part [SWAP]     swap
└─/dev/nvme0n1p3 259:3    0  3.6T  0 part /          ext4

The first column tells you the disk and partition names...
These are for use as source for reading all data from that disk or partition without the use of a filesystem .

A filesystem - as stated under FSTYPE - will organize and keep order on your files and folders.
NOTE: If you write to a disk or partition (e.g. /dev/sda, /dev/sda1 or /dev/nvme0n1 ... above), you will BYPASS the filesystem - and by that destroy what it has created.

Note here now: if you read data from e.g. /dev/sda and write it to /dev/sdb (if you have one), then you will have removed and overwritten ALL data on /dev/sda, replacing it with what was on /dev/sdb .

If you want a BACKUP of /dev/sdb - you will want to write that data to a FILE on e.g. the ext4 partition making up / - i.e. /SDB-BACKUP.bin or some such.
Only by that you will keep what already exist on /...

Now ponder thoroughly on the above, before you do anything more.

You will most likely prefer to do this
$ sudo dd if=/dev/sda of=/sda-backup-on-sdb.img
... or similar.
That is; if /dev/sdb/ has any filesystem and content on it - that you wish to KEEP.

+ 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Create image from unallocated hdd

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.