Questions tagged [loop-device]

A loop device allows any file to be mounted as a filesystem image. Not to be confused with a loopback interface in networking. Don't use this tag for questions regarding "for-loops" (use the "for" tag instead).

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Creating a loop device out of an SD card backup image results in a corrupt ext4 filesystem

I made a backup of my Raspberry Pi SD card. After creating a loop device out of the image, the ext4 filesystem seems to be corrupt although the original filesystem is OK. I've already tried different ...
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How to properly boot ISO9660 looped image with latest GRUB versions?

I'm trying to boot Ubuntu live ISO9660 image with GRUB 2.04 using these instructions. It is failing to boot with GRUB error error: unknown filesystem, even though I can browse as well the boot ...
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OSX: how to mount raspberry pi image file?

BACKGROUND The loop device is available in Ubuntu and is the first step to processing the rPi image with zerofree. The goal is to reproduce the UBUNTU example with OSX High-Sierra: UBUNTU example ...
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Creating a grow-on-demand loop filesystem without sparse files

I wish to create a file to loop mount as a root filesystem that grows dynamically as required (up to a limit). The commonly quoted solution to this is to use a sparse file, which would do exactly ...
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Why is mount mounting the directory to /dev/loop0 instead of the device? Can't write all my files to the directory as a result (since it's too small)

I want to write about 38 MB of files to a partition that is 100 MB large. However, when I mount that partition to the directory, it mounts to /dev/loop0 instead of /dev/sdc1 (in my example). This ...
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Mounting a Luks partition

I have backed up a drive with all its partitions using the command dd if=/dev/sda of=/media/oshirowanen/external-drive/backups-2019/full_drive_backup.img /dev/sda is an ssd which has a Linux OS ...
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Raw disk image from VDI file can be mounted using qemu-nbd but not loop device?

I installed a very old Slack version (3.2) on VirtualBox and then converted it to RAW format (ext2). However, for some reason I'm unable to mount it using losetup but qemu-nbd works fine. Why? I ...
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Recover deleted but mounted loop file/filesystem

By mistake, I deleted an lxc image file. The container is still running and the file is therefore not yet actually deleted until I stop the container. I'd like to avoid stopping the container as it is ...
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Getting snap to mount loop devices using direct I/O

How can I get snap to mount its loop devices in direct I/O mode on CentOS 7? When setting up loop devices manually, I can use losetup --direct-io 1, but can't see where to provide mount options to ...
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201 views

what is maximum loop devices for linux kernel?

i can include loop module for supporting loop files. loop module supports max_loop option. I've found examples with options loop max_loop 256 . My question, what is maximal supported loop devices? I ...
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How to make logical volumes on loopback block device available?

I have a file hdd.img being raw image of a hard disk. The harddisk has a BIOS/DOS partition table and its second partition is setup to serve as a the one single physical volume from which LVM creates ...
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122 views

Why there are 3 loop devices on my system right after boot?

I'll start this question by listing all drives available on my system right after the login into my Linux Mint 19.2 Cinnamon: # fdisk -l Disk /dev/loop0: 89,1 MiB, 93454336 bytes, 182528 sectors ...
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Hard drive failure imminent - blk_update_request - I/O error, dev loop3, sector 0?

I booted up my laptop today and I saw this error via dmesg: [ 49.388234] IPv6: ADDRCONF(NETDEV_CHANGE): wlp10s0f0: link becomes ready [ 49.671551] blk_update_request: I/O error, dev loop3, sector ...
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Delete /dev/loopX entry after detaching loop device

I created a loop device using losetup /dev/loop90 /tmp/disk1, where /tmp/disk1 is a 512M file I have created. Then the loop device was detached using losetup -d /dev/loop90. It was removed from the ...
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Why “udisksctl” and “mount -o loop” giving different root permissions after mounting?

I am trying to mount an iso using udisksctl and it appears that the bash scripts inside these are having only read permission [root@hostname ~]# udisksctl loop-setup -r -f /root/test.iso Mapped file /...
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How to create/populate /dev/loop* devices?

Background: I am setting up loopaes (see http://loop-aes.sourceforge.net/loop-AES.README) on a new install of Devuan ASCII 2.0.0. I built kernel 4.9.184 with CONFIG_BLK_DEV_LOOP=n as was instructed by ...
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292 views

Mount iso -o loop select loop device

I have a bash script where I mount an ISO to loop devices: mount -o loop my.iso /tmp/foo And it happens that at the same time in my OS (Linux Mint 19) I have an ISO image mounted, using the GUI ...
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How to split a bash loop on several nodes with Slurm?

I would like to split this loop : for i in $subset do srun Rscript my_script.R --subset $i done where $subset corresponds to seq 1 number . I would like to execute each value of i on multiple nodes....
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Can I specify a size space while using mount command?

I mount a *.img file, and want to copy some new files into it. But there is not enough space for me to place new files. Can I specify more size space while I use mount. ./Image: No space left on ...
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330 views

mounting loop not working with UUID

I have created a loop device and added it to /etc/fstab I got its UUID from the output of the blkid command (it does print a UUID for the particular device after running mkfs.ext4 /path/to/loop) ...
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ZFS Disk Image Performance

I am trying to move from LVM to ZFS as a backing store for raw virtual machine / disk images on a new server. I am using Ubuntu 18.04 and the SSDs are all Intel D3-S4510. The problem I am ...
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Redirect http->https, but exclude subdomain

I use Drupal, with a complicated multi-Domain setup, and have a local development site, that uses (locally) the dev. subdomain. So I want a .htaccess file that can be used on production AND ...
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Merge multiple files with different extensions using a loop in bash script [duplicate]

I have 100's of files of the form filename.0 filename.1 filename.2 filename.3 And they all have identical layouts which I want to merge together into one file using a loop in my bash script, I have ...
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Buffer I/O error on loop device

Lately, I have been getting Buffer I/O errors during boot time. Seemingly, it appears randomly and I could not be able to reproduce it. However, it happens in every 5-8 boot on average. Here is the ...
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260 views

How to automatically mount at boot? [duplicate]

I have a file, called "some.img", created with fallocate, that has a filesystem on it. I can mount the img file using mount -o loop some.img /media/where, and I see the filesystem. When I reboot, ...
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Issue with loop devices in Docker

I'm trying to build a virtual disk image in Docker. I'm able to create my empty file with dd and create the partitions with parted but once I try to make my filesystem it fails saying the device could ...
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3k views

How can an image file be created for a directory?

How can an image file be created for a directory? For example: https://unix.stackexchange.com/a/90794/674 shows that genisoimage can create an iso image file for a directory. I only know that an ...
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1answer
721 views

What do the partition table types and flags mean in the output of parted?

In the output of sudo parted -l: Model: WD My Passport 0748 (scsi) Disk /dev/sdb: 1000GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size ...
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215 views

Why does `losetup` need to associate loop devices with block devices? [duplicate]

man losetup says losetup is used to associate loop devices with regular files or block devices, to detach loop devices, and to query the status of a loop device. https://en.wikipedia.org/wiki/...
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Does “loopback” in a loopback file mean the same as in loopback IP address?

man pvcreate says pvcreate initializes a PV so that it is recognized as belonging to LVM, and allows the PV to be used in a VG. A PV can be a disk partition, whole disk, meta device, or loopback ...
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169 views

Dual Boot Linux Partition shows as Partition Table: loop in parted (Why?)

Recently I was checking into my partition scheme on my dual boot laptop (Peppermint OS, Windows 10). I was surprised by the output from parted /dev/sda12 (my Linux root partition) Model: Unknown (...
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923 views

How do I make `modprobe fuse` and `modprobe loop`, persistent?

This used to not be a problem, but now it is. I haven't changed anything significant so probably an update broke it. When I run VeraCrypt it complains that it couldn't set up loop device and suggests ...
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654 views

mkdir -p returns error if exists

Raspbian Stretch Lite: $ mkdir --help Usage: mkdir [OPTION]... DIRECTORY... Create the DIRECTORY(ies), if they do not already exist. Mandatory arguments to long options are mandatory for short ...
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388 views

Can't mount squashfs loop during initramfs

I am trying to mount a squashfs file during initramfs. I have included loop and squashfs modules. Currently using mount /foo.squashfs /mountpoint or mount -t squashfs -o loop /foo.squashfs /...
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763 views

losetup --detach not removing loopback device

I am trying to detach a loopback device. The losetup --detach presumably succeeds (no error message and return code 0) but the device is still there. Any ideas? root@Cassiopeia:~# losetup -a /dev/...
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4k views

Permanently mounting loop device

I created a file touch /datastore/virtual/pseudoblock created a loop device with it sudo losetup /dev/loop0 /datastore/virtual/pseudoblock (although I got a warning about its size) and then ...
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74 views

Loop Device eat up RAM [duplicate]

EDIT: Given link of another thread suggest that newer kernel do not have this issue but I am using latest kernel i.e. 4.18.5. Hence, this issue is either new or newer kernel have this bug In my setup,...
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90 views

loop device not matching file size

I have a sparse backing file (NTFS) (made via dd seek=) that's a partial image of a damaged disk. The size as given by ls matches the original disk. However, when looping it, /proc/partitions shows it ...
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5k views

Why does one need a loop device at all?

I previously used to create image files using dd, set up a filesystem on them using mkfsand mount them to access them as mounted partitions. Later on, I have seen on the internet that many examples ...
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1answer
1k views

What's the difference between direct-IO (“losetup --direct-io”) and “mount -o sync” for loop-devices?

I understand that without use of any flags, there are two caches involved with loop-devices. Once a page cache when writing to the file-system within the loop-device, and then again to the page cache ...
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18k views

What is the difference between mount and mount -o loop

I have a iso file named ubuntu.iso. I can mount it with the command: mount ubuntu.iso /mnt. After mounting it, I can see it from the outout of the command df -h: /dev/loop0 825M 825M 0 100% ...
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585 views

btrfs check /dev/loop0 -> ERROR: cannot open file system

I have a file formatted as a btrfs filesystem. I can loop mount it and use it normally. I'd like to run btrfs check on this file, but an error is generated. First I tried with just the file: $ ...
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454 views

Can losetup be made efficient with sparse files?

So my setup is like this. $ truncate -s 1T volume $ losetup -f --show volume /dev/loop0 $ mkfs.ext4 /dev/loop0 $ ls -sh volume 1.1G volume $ mount /dev/loop0 /mnt/loop Now I have a 1.1TB volume, as ...
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2k views

Cannot mount Matlab 2018a

I am using Ubuntu 18.04, and trying to moutn Matlab ISO using the following command: sudo mount R2018a_glnxa64_dvd1.iso /mnt/cdrom -o loop But terminal is responding back as: mount: /mnt/cdrom: ...
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408 views

Is it possible to boot a grub-mkstandalone created img file from cfg?

So I have a fully functional .img file created using grub-mkstandalone. I put this on a CD and it boots fine, the ISO loads great in a VM, etc... Now, what I want to do is link an existing grub.cfg ...
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2k views

How to take read all the partitions from eMMC dump

We have Beaglebone Black based custom board with 4GB eMMC and 256MB RAM. eMMC is partitioned as follows # parted --list Model: MMC MMC04G (sd/mmc) Disk /dev/mmcblk0: 3842MB Sector size (logical/...
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476 views

partition table on a disk partition; how to access?

I've made a TrueOS VM in VirtualBox, using a vmdk that virtualises a physical harddisk partition (sda5) as a complete disk. As a result, I now have a GPT/GUID partition table on that sda5 partition (...
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1answer
310 views

How to set ddrescue image sector size?

I have ddrescue image and want to recover data from it. But the image is taking wrong sector size it should take 4096 and the partitions are btrfs partitions. How to change the sector size? $sudo ...
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3k views

Debian. Can't umount loop device

Debian 8.2. I want to umount the /dev/loop5 device that I mounted, but I can't. I'm getting the message that /dev/loop5 is not mounted. Could anyone explain to me what I'm doing wrong here, ...
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268 views

Does `mount -oloop` use direct IO by default (when the kernel is new enough)?

Since the kernel started supporting it, losetup was modified to enable direct IO by default. This can avoid having redundant page cache and also has performance advantages. http://man7.org/linux/man-...