Swap file hard disk it appears to have holes

Question

guys i need to enable swap on my ubuntu system and i want to avoid swap on SSD or format my hard disk that doesn't contain the swap partition. So i was trying to create a file swap and use it but, following the ubuntu guide: https://help.ubuntu.com/community/SwapFaq i'm not able to figure out the problem. First of all i can't allocate the file with fallocate because it says operation not permitted, then i create a file with dd with all zeros but after setting the right permission and after calling mkswap, the command swapon fails saying: kipping - it appears to have holes. I want to use file swap to avoid create partition on a disk with already a whole partition, and i want it on the hard disk not on the SSD. Can you help me please? those are the steps that i did

The problem is that swapon got interrupted because the file appears to have holes. It is created using dd.

To resume what is the problem: my system has no swap at all. I want to add a new one on secondary hard disk, instead of primary SSD, but i want to avoid format it and create the partition. That is why i create the swap file. But when i try to active it with the command "swapon" i receive the error: it appears to have holes.

Hi and welcome. What version of Ubuntu? Why do you want a swap file and why not on the SSD where it would be much faster? — David, Mar 27 '21 at 11:52
Does this answer your question? How do I increase swapfile in Ubuntu 18.04? — vanadium, Mar 27 '21 at 11:57
Hi David, i'm using ubuntu 18.04. I want swap on hard disk because SSD will be saturated quite soon if i swap upon it because a huge amount of write op can decrease its life. — radamirez, Mar 27 '21 at 12:31
Hi vanadium i already follow that instruction but i receive the holes error. I'm using dd command to create the swap file. — radamirez, Mar 27 '21 at 12:36
You must sudo fallocate .... This will grab all the disk blocks in one contiguous block. Creating the file with dd allocates disk blocks a few at a time, with no guarantee of contiguous groups of blocks, thus, the complaint about "holes". — waltinator, Mar 27 '21 at 17:29
Hi, this is different of what the tutorial says but i tried fallocate, but it says operation not permitted — radamirez, Mar 27 '21 at 18:41
Welcome to AskUbuntu! I believe that this is the answer you require. https://askubuntu.com/a/796997/225694 you'll note that sudo is required for all the commands in the answer that create and implement the swap. — Elder Geek, Mar 27 '21 at 22:31
Does this answer your question? How do I add swap after system installation? — Elder Geek, Mar 27 '21 at 22:32
No that question regard the partition swap, i want to enable a file to swap — radamirez, Mar 27 '21 at 22:50

score 1 · Answer 1 · answered Mar 29 '21 at 08:30

To Enable Hibernation in 20.04 Using a Swapfile:

I used this method yesterday to increase my swapfile size and enable hibernation, (optional). Last paragraph is how I search for holes.

Increase swapfile size to match RAM size up to 8GB.

Check the swap that is in use:
```
sudo swapon -s
```

If swap partition(s) are found:

sudo swapoff -a
sudo nano -Bw /etc/fstab

Add # before the UUID of the swap partition(s):

# UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX   none   swap    sw     0       0

Add a line for the swapfile, if one does not exist:
```
swapfile   none    swap     sw      0       0
```

Create the swapfile:

sudo fallocate -l XG /swapfile*

where X is swapfile's size in GB:

sudo mkswap /swapfile
sudo chmod 0600 /swapfile
sudo swapon /swapfile

Reboot:
```
sudo reboot
```

Add resume location and offset to grub.cfg:

Edit /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX resume_offset=XXXXX"

Use UUID from root.

Use offset from:

sudo filefrag -v /swapfile |grep " 0:"| awk '{print $4}'

Update GRUB:
```
sudo update-grub
```
Test hibernation:
```
sudo systemctl hibernate
```

A hibernate button can be added using GNOME extensions.

Note that there is a slight possibility of getting holes in a swapfile when creating it with fallocate. /var/log/syslog can be searched for the phrase swapon: swapfile has holes to ensure there will be no data loss.

Thanks but those are just the step that i did. i just want to figure out the error. — radamirez, Mar 30 '21 at 10:26
Did I read that your system has a swap partition and a swapfile? — C.S.Cameron, Mar 30 '21 at 13:30
No my system has no swap at all. I want to add a new one on secondary hard disk, but i want to avoid format it and create partition. That is why i create the swap file. But when i try to active it with the command swapon i receive the error: it appears to have holes. — radamirez, Mar 31 '21 at 10:17
Are you creating it on the SSD and then moving it? I missed why you are not just adding a swap partition to the HDD? That would be easy. — C.S.Cameron, Mar 31 '21 at 12:31
I already tried to create first on SSD and then move it on HDD but the same error happen. I know that is easy but doesn't figure out the holes problem. — radamirez, Apr 01 '21 at 13:13

Swap file hard disk it appears to have holes

1 Answers1

To Enable Hibernation in 20.04 Using a Swapfile: