What are all the Disk /dev/loop?' things with fdisk -l

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1

What are these? when doing a ‘fdisk -l’ ?
With Leap 15.2 and WIn 10 and Win 7 there are q5 of them in the output listing.

**Disk /dev/loop0: 31 MiB, 32440320 bytes, 63360 sectors**
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

**Disk /dev/loop1: 97.8 MiB, 102486016 bytes, 200168 sectors**
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

**Disk /dev/loop2: 217.9 MiB, 228478976 bytes, 446248 sectors**
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

**Disk /dev/loop3: 64.4 MiB, 67477504 bytes, 131792 sectors**
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

**Disk /dev/loop4: 162.9 MiB, 170778624 bytes, 333552 sectors**
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
2

It’s a bit hard to guess, because you have not said what you are doing.

A loop mount is when you have a file containing a disk image and mount that as if it were a disk.

If I mount a downloaded iso (usually for a linux distro), that will give a loop mount.

If I boot a live DVD or a live USB, there are often loop mounts there.

3

Yesterday I downloaded the Leap live iso, and put it on a USB stick, then I booted from the live stick to check it out.

BUT those Loop things have been there for several weeks. Long before I D/L’d the live iso and put it on a stick.

AFAIK, I have not mounted an iso, nor the USB live stick.

How do I check if there is something mounted that shouldn’t be?

all of those 15 LOOPs relate back to HDDs Leap partitions & Win10 & Win7 on my hard drives. I don!t see anything that indicates an iso nor a USB in the list. I will post the complete list if you want.

The FULL listing of fdisk -l is here
https://susepaste.org/42829074

4

Hi
So what does the output from the lsblk command show?

5

HA, I was just getting ready to post the output from lsblk -f
It is here SUSE Paste

Looks like all those 15 LOOP’s are related to Snap.
Can I clean it up, or am I stuck with it?

6

Hi
Maybe restart snap, but maybe the snap things are not cleaning up after exiting…

7

First, not just images but just about any file system can be mounted in a loop device.

I wrote a Wiki article for anyone who wants to set up and use a loop device, avoiding plenty of obsolete info and hopefully re-describing in easier to understand words…

https://en.opensuse.org/User:Tsu2/loop_devices

I’ve never investigated the nuts and bolts of how snap works, but it makes plenty of sense to deploy on a loop device which provides a good level of isolation from the rest of the system.

So,
Bottom line,
If you simply want to terminate those snap apps by unmounting the loop devices, read my Wiki article…
And I assume that unless you’ve implemented something that’s automatically mounting those devices, once unmounted I wouldn’t expect them to show up again until you want them.

TSU

8

They are being mounted at boot, but I don’t remember doing anything that would cause that. I did open Snap and only found what was installed using it.
I am looking for ‘auto’ mounting, but so far have not come across anything that helps stop extraneous mounting(ie: anything but swap, / and /home).

I am looking at your WiKi page to see if it will help.

9

I did that, but no help. I NOW notice at shutdown where those ‘snap’ loops are being unmounted, but they are there again after another start. They are being auto mounted and I can’t find out what I did to cause that.

I do know that until very recently, when I did an ‘fdisk -l’ only my physical devices and partitions were listed. I can’t pin point when those loop devices started showing up.

It is likely some dumb newbie thing I did and can’t remember!

10

Gone now! I don’t know what most of them did, so I removed ‘snapd’ via YaST.
I’ll see what other ‘strangeness’ happens the next couple of days.