Ubuntu – Problem accessing old data on btrfs /home in ubuntu 14.04

btrfsdata-recoveryfilesystempartitioning

I recently did a fresh installation of ubuntu 14.04 64 bit on my pc. Previously I was dual booting ubuntu 14.04 with windows(both 32 bit). My hdd is 500 GB. The previous structure of the hard disk was as follows:

partition 1:type-primary, size:100GB, file system:NTFS(windows)
partition 2:type-primary, size:100GB, file system:NTFS(data)
partition 3:type-primary, size:100GB, file system:NTFS(data)
partition 4:type-extended, size:(remaining), contents:following:-
- sub-partition 1: size:100GB, file system:NTFS(data)
- sub-partition 2: size:1GB, file system:ext4(/boot)
- sub-partition 3: size:50GB, file system:ext4(/)
- sub-partition 4: size:16GB, file system:ext4(/home)
- sub-partition 5: size:2GB, file system:swap

Now first I copied data from partition 2 into partition 3. then after creating ubuntu 14.04 live usb on a 8GB pen drive, I deleted partition 1, 2 using Gparted in live session and created a new partition of size 106 GB. Then I copied partition 3 data (both backup of part. 2 and data of part. 3) into new 105GB partition (let's call it root_new) of type:primary and file-system:btrfs. then I copied sub-partition 1 data into root_new and old /home data in root_new. I put all these in separate directory to identify them later. Then I archived old /etc in root_new. After this total backup size was 48GB approx.

Then I deleted partitions 3, 4 and created a new partition on remaining free space of type:primary and file-system:btrfs. let's call it home. Its size is approx. 370GB. Then I copied root_new backup data in home. Then I deleted root_new and created new partitions as follows:

partition 1:type-primary, size:1GB, file-system:btrfs(/boot)
partition 2:type-primary, size:100GB, file-system:btrfs(/)
partition 3:type-swap, size:remaining.

Then I installed ubuntu in the partitions with configurations shown in new part.1, 2, 3 (with formatting) and using home as /home without formatting so that I could access backups on home after installation.

Ubuntu installed successfully. I choose not to encrypt my home directory. But after login I did not find my backup data on /home. There was only my home directory.

Here is output of df command:

$ df -lh
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3       100G  3.2G   96G   4% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            986M  8.0K  986M   1% /dev
tmpfs           200M  984K  199M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            996M  156K  996M   1% /run/shm
none            100M   52K  100M   1% /run/user
/dev/sda2       360G   47G  312G  14% /home
/dev/sda1       1.0G   35M  861M   4% /boot

As you can see /home is 14% used.

Here is output of ls -la /home:

$ ls -la /home
total 0
drwxr-xr-x 1 root root   8 May  2  2015 .
drwxr-xr-x 1 root root 176 May  2  2015 ..
drwxr-xr-x 1 kutu kutu 480 May  2 18:00 username

And I'm sure I put backups right under /home in directory which are not showing.

Here is another command.

$ sudo btrfs filesystem df /home 
Data, single: total=47.01GiB, used=46.48GiB
System, DUP: total=8.00MiB, used=16.00KiB
System, single: total=4.00MiB, used=0.00
Metadata, DUP: total=1.00GiB, used=65.45MiB
Metadata, single: total=8.00MiB, used=0.00

Please help me to recover these backup data.

Best Answer

I solved the problem!

First i noticed in /etc/fstab that / was mounted with subvol-@ but /home as subvol=@home. So I googled and found the solution.

Here are the steps (assuming /home is on /dev/sda2) I did:

Create a directory to mount the total partition.
```
sudo mkdir /mnt/old_home
```
Mount the partition.
```
mount -t btrfs /dev/sda2 /mnt/btrfs
```
Copy contents from the backup directory to suitable location.

And that's it.

Related Solutions

Ubuntu – New ext4 partition and used space

There's nothing to fix, and this is perfectly normal.

ext4 creates a lot of overhead before any files are created. It does not mean it is "worse" than ext3. If you fill that partition with files, you will notice that ext3's (and NTFS's) overhead will grow proportionally with the files, as with ext4 it will basically remain constant forever.

By "pre-allocating" the overhead, it can manage it much better than a growing one. So ext4 is just doing now what ext3 would do later.

Besides, 27G may look a lot, but it's still a mere 1.5% overhead. Compare that to the old days of FAT, where slack space could eat anything from 5% to 30% of your partition space, and you'll notice how greatly things have evolved since then.

Also, I strongly recommend against using -m 0. Reserved space is there for a reason: it lowers the fragmentation chances and saves some space for fsck. It is reserved only from users, but root (and thus all your software installs) can fully use it. If you think 5% is excessive, leave at least 1% .

Remember: there's no fragmentation nightmares in ext. But this beauty comes at a price. It needs free space as room for proper management. Give it to him and things will run much smoother. Besides, who ever uses their HDD beyond 90% before buying a larger one? So what's the problem about a 5% reserved space? It may save you the next time you accidentally create a dozen-GB file that fills up the whole partition and end up crashing the OS due to lack of space for other processes.

For a more detailed, further technical reading, read here

Ubuntu – How to combine separate partitions created by initial install of kubuntu

Open the other partition in the file browser and press ctrl+L. You will be shown a path. Copy it. Then open a terminal and enter

cd "[whatever path]"

Where [whatever path] is the path you copied. Keep the quotes. They don't do any harm and make things easier if there are spaces or some other characters in the path. This will set your location in the current terminal to the mount point of your second partition.

Then enter these commands:

sudo chown -R [your user name] .
sudo chmod -R 777 .
sudo chown -R root "lost+found"
sudo chmod -R 700 "lost+found"

This will set the rights the way you want them to be. The first command makes you the owner of everything on the partition. The second command gives you all rights to it, but also every other user of the computer, in case you want to have several accounts and share files this way. If you don't want to do so, change 777 to 700 (others can't do anything) or to 722 (others can only read). The last 2 commands set everything back to the previous state for the (hidden) folder "lost+found" which is a special folder which you probably never will not have to use.

Best Answer

Related Solutions

Ubuntu – New ext4 partition and used space

Ubuntu – How to combine separate partitions created by initial install of kubuntu

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