fdisk -l:

Disk /dev/sda: 931,5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes`

parted -l:

Model: ATA WDC WD10EZEX-21W (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: loop
Disk Flags: 

Number  Start  End     Size    File system  Flags
 1      0,00B  1000GB  1000GB  ext4

goal: that drive should have 1 encrypted partition with all my data, but not operating system, and (not necessarily) 1 unencrypted partition

This drive has 200 GB of data on it. (only data, no system files - OS is on 250 GB SSD). I don't have any other storage where I can store the files while operating with that drive (my ssd has ~50 gb of free space).

I can resize that primary partition, but I can't create new partition in free space: gparted says only 1 primary partition can exist on this drive. help?

OS: Ubuntu 16.04

  • What do you get from sudo file -kLs /dev/sda? – ctrl-alt-delor Jan 7 '17 at 11:38
  • /dev/sda: Linux rev 1.0 ext4 filesystem data, UUID=4a48b072-5b30-49f4-b4a7-f8b4ad4e5a37 (needs journal recovery) (extents) (large files) (huge files)\012- data @richard (edit: fixed formatting) – nullifiedcat Jan 7 '17 at 14:15
  • You output form sudo file -kLs /dev/sda shows a file-system and sda is the raw device, therefore you do not have a partition-table on this device. Note also please ignore needs journal recovery, they usually say that when mounted. – ctrl-alt-delor Jan 9 '17 at 10:44

As identified by richard, the filesystem starts on the very first sector of the disk: you have no partitions. To create an encrypted partition, you will need to create a partition table first. And you do need to have two partitions if you want to have an encrypted partition, because you need some non-encrypted space for the bootloader.

You can create a partition table without losing your data. It's a delicate task, so double-check that your backups are up-to-date, but it can be done.

The ext4 filesystem leaves the first 512 bytes unused, and an MBR partition table fits within the first 512 bytes of the disk, so you have room for an MBR partition table. (Note that it has to be MBR, not GPT.)

First, boot some rescue media. Do not attempt to do any of this while the filesystem is mounted. SystemRescueCd is good for this kind of things.

If more than half the disk space is free, then you can create a partition in the second half of the disk as follows:

  1. Determine the path to the disk device. Note that a rescue system might name the disks differently from your normal system. Here I'll assume that the path is /dev/sda.
  2. resize2fs /dev/sda to shrink the filesystem about as much as it'll go. You can see how much space is free with tune2fs -l /dev/sda.
  3. Run fdisk /dev/sda. Fdisk will create a “dos disklabel”, i.e. an MBR partition table, in memory. Enter n and create a new primary partition that starts after the end of the filesystem. Enter w to write the new partition table and exit fdisk.
  4. Copy the filesystem to the new partition with head -c SIZE /dev/sda1 where SIZE is the size of the filesystem after shrinking.
  5. Verify that the data new partition is safe.
  6. You can now create partitions to span the first half of the disk, where the old copy of the filesystem is located.

If more than half the disk is in use then you're in for quite some pain. I think you can do it by first converting the data to an LVM volume with blocks, then shrinking the filesystem, the logical volume and the physical volume, and using gparted to move the start of the physical volume. But I've never done anything like this, so triple-check your backups.

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  • I edited the question, to make it clearer, that the operating system is not on this disk. It is on a separate SSD, therefore all the stuff about rescue disks can be ignored, you just have to unmount the disk that you are working on. Other than that this answer should be of use to you. – ctrl-alt-delor Jan 9 '17 at 10:34

If you can have only one partition, then it suggests that you have no partition table: you are just using the raw disk. I looked up Partition Table: loop, and found a lot of stuff, that seems to confirm that you are using the raw device.

It should be possible to move the file-system, and insert a partition table that points points to it as partition one. You could then proceed to add another partition etc.

However I suspect the probability of you not trashing your data to be close to zero. If you have another small device you could practice a few times, but if reality turns out to be different from the practice then, your data may disappear.

I did this once, and was in hot sweats, with it broken for hours, before getting it working. Another time I accidentally wrote over the data.

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  • I think I actually can just wipe that drive.. It just has backups and my downloads folder. – nullifiedcat Jan 7 '17 at 14:20
  • I'll wipe it if there is no way to fix that without wiping – nullifiedcat Jan 7 '17 at 14:20

It may be possible to boot up a portable distro, resize the partition as small as possible with parted, create another, encrypt it, move the data over to the new encrypted partition. This now leaves multiple options: keep the old partition to be used as /boot (which may be necessary to run GRUB, then unlock the encrypted drive), or delete the old partition, resize the encrypted partition to use the entire disk, and use GRUB's built-in crypto module to unlock the new LUKS volume without need for a /boot partition (which personally I have found to be terribly slow at unlocking drives).

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  • 1
    I can't create new partition on that drive! "It is not possible to create more than 1 primary partition" – nullifiedcat Jan 7 '17 at 10:33
  • The partition table should be MBR (or GPT), which supports 4 primary partitions (255 on GPT, IIRC), one of which can be divided into multiple secondary partitions. If you haven't already, resize the partition and try to create the partition again. – Kenneth B. Jensen Jan 7 '17 at 10:42
  • 1
    parted says "Partition Table: loop" (not mbr or gpt) – nullifiedcat Jan 7 '17 at 10:50
  • Does fdisk -l display partitions? If so, it would be possible to use fdisk /dev/sda, create a new MBR partition table, recreate the partition (not the filesystem, which would not be modified) based on disk sectors, and run grub-install, without losing data, then follow my advice in the answer. – Kenneth B. Jensen Jan 7 '17 at 10:53
  • @KennethB.Jensen if you creat a partition table, then first ensure that file-system it out of the way, so that you do not write over it. – ctrl-alt-delor Jan 7 '17 at 11:34

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