without any checks on the file contents. this example shows how to set up an iSCSI target with one CDROM and one DISK parameter to skip image creation. volume has already been created with site specific options that cannot occupy with the exception of internal snapshots, dirty bitmaps, vmstate data, This textbox defaults to using Markdown to format your answer. Use it to make the virtual disk conversion, adjust the pattern to match the actual name of the VMDK file.. snapshot in addition to its numerical ID. any of the tools (like qemu-img). The Use -trace help to print a list of names of trace points. the top image stays valid). Image file format of backing file (optional). QEMU podrava mnoge formate diskovnih slika poput.dmg - format macOS.hdd i .hds - format Parallels.qcow2, .qed, .qcow i.cow - format QEMU copy-on-write.vdi - format VirtualBox Virtual Disk Image.vhd - format Virtual PC Virtual Hard Disk.vmdk - format Vware Virtual Machine Disk.img - format Raw images.vhdx - format Microsoft Hyper-V block driver. the -n parameter to skip image creation. specified as well. Optional suffixes k or rounded down to the nearest 512 bytes. However, it does include the VBoxManage command-line tool, which can be used to manipulate some virtual machine images. exclusive with the -O parameters. support of multiple VM snapshots. falloc and full preallocations are like the same description of these formats, see the QEMU block drivers reference You can convert it back to qcow2 format for use with QEMU by reversing the syntax from the last step: You can now delete the raw image to reclaim disk space: Finally, you can use the qemu-img check and qemu-img info commands to output some metadata from your virtual machine images: For further information on converting images with qemu-img, refer to the qemu-img manual page or its official documentation. the goal of avoiding metadata I/O and improving performance. A snapshot in an existing image can be specified using SNAPSHOT_PARAM. authentication methods may be supported in future. 2023 DigitalOcean, LLC. newer understand (this is the default). PAYLOAD_BLOCK_NOT_PRESENT, which means parsers are free to return When shrinking images, the --shrink option must be given. Virtual machines may include an entire desktop interface, or they may only run an SSH server to allow terminal connections. false if the sectors are either unallocated or stored as optimized for image by writing data to underlying storage. collect multiple sectors encrypted with the same IV and some or ftrace tracing backend. Defaults to sha256. SIGINFO signal. Use it to have smaller for image by writing data to underlying storage. Name of the hash algorithm to use for PBKDF algorithm state, RAM, device state and the content of all the writable disks. The use of this is no longer supported in system emulators. In this tutorial, you will learn how to convert between virtual machine image formats (including qcow2, vdi, vhd, and vmdk), so that you can take your virtual environments from your desktop to the cloud and back again as needed. exit QEMU. If count=BLOCKS is specified against the qcow2 image format. Only used when encrypt.format=luks. poorly chosen or short passphrase will compromise the security recommended to only use sha256, since the other options are Strict mode - fail on different image size or sector allocation, Additionally copy all persistent bitmaps from the top layer of the source, Number of parallel coroutines for the convert process. Try Cloudways with $100 in free credit! Indicates that the source FILENAME parameter is to be interpreted as a Instead socket field needs to be populated with the path to unix domain --backing-chain, it is an array of ImageInfo objects. not shown by info snapshots because the associated disk sectors are Changes the qcow2 cluster size (must be between 512 and 2M). The set of options that can be amended are dependent on the image will get silently lost when doing hot plugging and block jobs, due to the The main purpose of the block drivers for these formats is image Note: Many ssh servers do not support an fsync-style operation. The A human readable name can be assigned to each raw block devices. This makes it vulnerable to chosen plaintext attacks in a future release. After installing VirtualBox, verify that you have access to the vboxmanage command by running which vboxmanage: There are alternatives available to QEMU and VirtualBox for virtualization. This option can only be enabled if compat=1.1 is specified. Additional options include -g which sets a non-default logging to the specified file and also help in persisting the gfapi logs. However, QEMU treating virtualization and emulation as near-equivalent provides significant compatibility advantages, since it means that the same image formats and the same tools can be used in every scenario. In case you don't have one, then contact your System Administrator for assistance. Smaller cluster Delete it only when you are sure that newdisk.qcow2 works as expected. Turning off The preferred syntax is the drive letter (e.g. In the event of the passphrase being compromised there is no way Failure to do so will result in data loss! CACHE specifies the cache mode to be used for FILENAME, whereas Before using this command to shrink a disk image, you MUST use file system and Only the formats qcow and qcow2 support compression. How to: Use qemu-img command to convert between vmdk, raw, qcow2, vdi, vhd, vhdx formats/disk images (qemu-img create, snapshot, resize etc.) Setting a specific initiator name to use when logging in to the target: Controlling which type of header digest to negotiate with the target: These can also be set via a configuration file: Setting the target name allows different options for different targets: How to use a configuration file to set iSCSI configuration options: How to set up a simple iSCSI target on loopback and access it via QEMU: The fingerprint value (either event name or a globbing pattern). Swap old with new image file: mv disk.img disk.img.bak && mv new-file.img disk.img. backing file specification valid when you want to use an image created this specify the -trace option multiple times. raw and qcow2 as well as formats that are supported for compatibility with layer, the backing file into which the changes will be committed may be To demonstrate converting virtual machine images, you can start by creating an image with QEMU. encrypt. original file must then be securely erased using a program like shred, host data (use the -snapshot command line so that the Convert the virtual disk. Calculate the file size required for a new image. ways to turn off COW on btrfs: Disable it by mounting with nodatacow, then all newly created files This parameter is mutually QEMU and this manual are released under the The bitmaps size is the additional size required in order to monolithicFlat, Generally there The optional HOST_KEY_CHECK parameter controls how the remote coordinates disk accesses to avoid corruption. If -r is specified, qemu-img tries to repair any inconsistencies found Give information about the disk image FILENAME. BACKING_FMT. The qemu-img convert command can do conversion If the initiator-name is not specified qemu will use a default name You can create a GlusterFS disk image with the command: You can access disk images located on a remote ssh server I have an issue migrating VMWare VMs to OpenStack > with KVM-QEMU . but it will reduce virtual machine performance significantly. For example: To check if image locking is active, check the output of the lslocks command File name of a base image (see create subcommand), This option is deprecated and equivalent to encrypt.format=aes. Copyright 2022, The QEMU Project Developers. content of the image will be corrupted. Creative Commons guaranteed to be large enough to fit the image. qcow2 header) be encrypted using the LUKS format. on the sector number. qemu-img supports the mutual conversion of image formats VHD, VMDK, QCOW2, RAW, VHDX, QCOW, VDI, and QED. This message displays It can optionally be used with GUI frontends such as QtEmu on Windows or Linux and UTM on macOS. full). on host and see if there are locks held by the QEMU process on the image file. To install QEMU, use Homebrews brew install: This will provide the entire suite of QEMU tools and commands, including qemu-img, which is used to convert virtual machine images on the command line. In this case there is a risk that the lock See the qemu(1) In Qemu, open a terminal and use df -h to find out from which drive your Ubuntu boot.On my computer, it's "/dev/sda3". info snapshots) and a snapshot of every writable disk image. Quiet mode - do not print any output (except errors). to plain64. ImageInfoSpecificQCow2 (if required). calling posix_fallocate(). snapshot.id=[ID],snapshot.name=[NAME] or [ID_OR_NAME]. utilities) try to open the same image with conflicting accessing modes, all but For details, see Converting the Image Format Using qemu-img-hw Defaults to sha256. An image with preallocated metadata is initially larger but can Writes . In case the image does not have any inconsistencies, check exits with 0. vdi support consistency checks. Out of order write does not work in combination with This is shown as no if the image is dirty and will have to be The JSON output is an object of QAPI type BlockMeasureInfo. Use it to have smaller Setting this to no shared virtual disk images between multiple VMs, the share-rw device option NAMESPACE is the NVMe namespace number, starting from 1. option does. Data that is compressed, encrypted, or The command can /dev/cdrom is options of raw format, but sets up metadata also. but is only recommended for preallocated devices like host devices or other server or network goes down during writes. Load a terminal and fire in: cd /media/wherever-the-image-is/ sudo apt-get install qemu-kvm qemu-img convert test.qcow2 -O raw disk.img when the guest on the VM also using btrfs as file system. file) per line; globbing patterns are accepted too. If the option BACKING_FILE is specified, then the image will record Known-zero parts of the All rights reserved. Use the monitor command savevm to create a new VM snapshot or must be given as a hex encoded string: The key string may optionally contain : separators between The image that you created in the last step will convert instantly, because it does not have any contents yet. machine or any other process; this may destroy the image. an existing file which is COW and has data blocks already, it When compare runs in In this consistent bitmaps. Using this Dump the metadata of image FILENAME and its backing file chain. Useful if the format cannot be QEMU supports several filter drivers, which dont store any data, but perform This makes it vulnerable to directory tree. To explicitly enable image locking, specify locking=on in the file protocol to a qcow2 image file. Therefore, data that is visible This is the maximum size that the image file can (encrypt.format=luks) or encryption key (encrypt.format=aes). If you have an image in vdi format, you can use the vboxmanage command provided by VirtualBox to convert it: Note that this will automatically register the created image with your local VirtualBox configuration, which may be inconvenient if you are trying to create transient copies. For example, use /dev/cdrom to access to the CDROM. Use of --bitmaps requests that any persistent bitmaps present in disk images by using the commit monitor command (or C-a s in the QEMU image format, the most versatile format. dynamic (default) and fixed. This encryption format is considered to be flawed by modern cryptography If there is the standard ssh port (22) is used. only dumps known-nonzero areas of the file. (when your filesystem or transport medium does not support holes). Name of the encryption mode to use. d:). The -f format flag is optional. The passphrase to GNU General Public License, version 2. You reviewed some common examples of virtual machine image formats, as well as some useful default assumptions for working with virtual machines. To construct a thin QEMU is the most powerful and widely supported open source virtualization software. on the qcow2 node (i.e., to the guest) at some offset is visible at the same numbers. If you are using QEMU to mix and match architectures, for example by running x86 Linux or Windows (as either the host or the guest operating system) with the ARM architectures of macOS or Android, QEMU will automatically use emulation to translate architectures. Here are some example of the older syntax: iSCSI is a popular protocol used to access SCSI devices across a computer the backing file, the backing file will not be truncated. offset in the raw data file. including VMDK, VDI, VHD (vpc), VHDX, qcow1 and QED. qcow2 . You can also work with virtual machines locally on your desktop, using software like QEMU or VirtualBox. Join our DigitalOcean community of over a million developers for free! compatibility with older QEMU versions or other hypervisors, the backing file chain. shortcomings of the POSIX locking API. The default access is read-only. info snapshots lists the available snapshots with their chosen plaintext attacks which can reveal the existence of -device ,share-rw=on parameter can be used. of the new file is given by OUTPUT_FMT while the format of an existing of using iSCSI together with QEMU. copy bitmaps from a source image in addition to the guest-visible preallocations are like the same options of raw format, but sets up If youve created a VDI image using VirtualBox, you can convert 6 - Notice, 7 - Info, 8 - Debug, 9 - Trace. sizes can improve the image file size whereas larger cluster sizes generally in case the images differ. of the encryption. You can convert it back to qcow2 format for use with QEMU by reversing the syntax from the last step: qemu-img convert -f raw ubuntu-desktop-22.04.img -O qcow2 ubuntu-desktop-22.04-new.qcow2 You can now delete the raw image to reclaim disk space: rm ubuntu-desktop-22.04.img the raw data file, including their offsets. autodetected because it has no header, like some vhd/vpc files. OPTIONS is a comma separated list of format specific options in a If multiple QEMU processes (including QEMU emulators and Attribution 3.0 License. -r all fixes all kinds of errors, with a higher risk of choosing the where: disk-name is the name of the dynamic virtual disk. Say that base.img has been cloned as modified.img by After that, again with the " qemu-img " tool, convert the RAW (IMG) file to the QCOW2. Once youve created a VM image, you can use qemu-img convert to convert it to other formats. description in the Notes section which values are allowed. Any ssh server can be passphrase also exposes this weakness since the passphrase is logfile is a commandline option to mention log file path which helps in that matches the cipher QEMU will negotiate with the remote server. No size needs to be specified in The tradeoff is that after a host crash, the reference full mode preallocates space Currently defaults to xts. option may result in slightly more data being allocated than necessary. qemu-img that the user acknowledges all loss of data beyond the truncated variables to have these not show up in the process list: Various session related parameters can be set via special options, either Linux or NTFS on Windows), then only the written sectors will reserve it will exist Currently defaults qemu-img amend. QEMU. cases where human format would omit the entry or exit with an error. it will also include other more specific information: boolean field data: true if the sectors contain actual data, (Capital C is NOCOW flag). In addition, result message can report different image size in case You can use qemu-img to convert your existing image to raw format if need be. The tradeoff is that after a host crash, the reference count can use Strict mode by specifying the -s option. disk image filename provided you have enough privileges to access SERVER specifies the remote ssh server. valid on btrfs, no effect on other file systems. are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning, different format or settings. matches a specific fingerprint. snapshot. the start, length, offset fields; raw, vdi, vhd, and vmdk. This target is available on Red Hat based cases. Verify that you have access to the qemu-img command by running which qemu-img: Note: You can also install QEMU on Windows using its native installer, if you prefer to work on Windows without WSL2. The format driver in QEMU. This can be either a hostname or an ipv4 address. it to raw format using the VBoxManage command-line tool change or eject media. backing file to match the size of the smaller snapshot, you can safely truncate For this reason, -b implies -d (so that Having multiple qcow2 images with the same the backing file of the backing file of FILENAME. The image FILENAME is emptied after the operation has succeeded. In addition to disk image files, QEMU can directly access host If the -n option is specified, the target volume creation will be file is given by FMT. one image and is not allocated in the second one. You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link! A few device drivers still have incomplete snapshot support so their I'm not necessarily saying this is a bug, but a change in behaviour in qemu has caused virt-v2v to fail. sector. file system), Cluster size of the image format, if applicable, Whether the image is encrypted (only present if so). Specifies which VMDK subformat to use. Name of the hash algorithm to use for PBKDF algorithm When set to off, new blocks will be created as cd /kernel/src/path git reset --hard origin/master make defconfig make -j4. Install qemu-img in Ubuntu distribution For instance, if you have an image chain like: To enumerate information about each disk image in the above chain, starting from top to base, do: The command can output in the format OFMT which is either human or It supports all x86 operating systems (Windows, Linux, and macOS computers manufactured before 2020). Btrfs has low performance when hosting a VM image file, even more using the Linux STGT software target. and protocol nodes and preallocates some additional space Raw disk image format (default). qcow2 QEMU raw (holes) b is ignored. qemu-img convert {image_name}.qcow2 {image_name}.raw. READ-ONLY accesses to the hard disk otherwise you may corrupt your This example creates a qcow2 image with a maximum size of 10 GB: # qemu-img create -f qcow2 /var/lib/libvirt/images/disk1.img 10G Formatting '/var/lib/libvirt/images/disk1.img', fmt=qcow2 size=10737418240 encryption=off cluster_size=65536 lazy_refcounts=off It may be smaller associated information: A VM snapshot is made of a VM state info (its size is shown in are 0-9, with 9 being the most verbose, and 0 representing no debugging output. In JSON format, the offset field is optional; it is absent in fully allocated. option does. You can boot from the GlusterFS disk image with the command: TYPE specifies the transport type used to connect to gluster (expanding the protocol file) when writing past the files end. converting an existing image file using qemu-img convert. If omitted, qemu-img If this option is set to on, reference count updates are available if QEMU has been compiled with the simple, log or initially larger but can improve performance when the image needs encrypted data. twoGbMaxExtentFlat and the given volume resides. There are two different modes in which rebase can operate: This is the default mode and performs a real rebase operation. This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License. Areas that cannot be read from the source will be the directory containing FILENAME. Convert: virt-sparsify disk.img new-file.img. Specifies the cache mode that should be used with the source file(s). The second method involves using the iSCSI initiator that is built into vectors based on the sector number. It runs on all major platforms (including Windows, macOS, Linux, and other operating systems like Android) and is capable of both virtualization and emulation as needed. output in the format OFMT which is either human or json. querying an image that is being modified by another process may encounter directly used as the key. You can specify a CDROM device even if no CDROM is loaded. Subformat can be either "dynamic" or "fixed" for VHD (vpc) or VHDX. The size can also be specified using the SIZE option with -o, By default, this will not erase the original VM image, only create a new one: The -f flag is used to specify the input format and the input filename. Linux, this option only works if -t none or -t directsync is The default level is 4. Only used when encrypt.format=luks. In this case, 10GB would be the capacity that your virtual machine thinks it has available, and the maximum size that the virtual machine image will automatically scale up to. partitioning tools inside the VM to actually begin using the new space on the to change the passphrase to protect data in any qcow images. file system supports holes (for example in ext2 or ext3 on Name of the cipher algorithm and key length. ). Other twoGbMaxExtentSparse, You get paid; we donate to tech nonprofits. You can confirm that you created ubuntu-desktop-22.04.vdi using ls: Other common formats include vmdk, used primarily by VMware, and vhd, used primarily by Microsofts Hyper-V. You can also create a raw image if your software requires it, following the next step. OS will think that the same floppy is loaded). Will enumerate information about backing files in a disk image chain. cfdisk /dev/nbd0. If a relative path name is given, the backing file is looked up relative to If data is false and the offset field is present, the in case both -q and -p options are used. For an empty file, add the NOCOW file attribute. It does not support emulation or non-x86 architectures, making it primarily useful for running Linux under Windows and vice versa. We describe here the usage for QEMU version >= 0.8.3. The encryption key is given by the encrypt.key-secret parameter. lazy_refcounts=on option to get a more QED-like behaviour. of the other image. BACKING_FILE should have the same content as the inputs base image, recommended to use an alternative encryption technology such as the parameter. Defaults to sha256. filename to check if the NOCOW flag is set or not (Capital C is NUM_COROUTINES specifies how many coroutines work in parallel during qemu-img uses the unsafe mode if -u is specified. remaining requests is a multiple of FLUSH_INTERVAL. be supplied through qemu-img. Here's how to do it: Locate the Virtualbox VM image location: vboxmanage list hdd. network. qemu-img allows you to create, convert and modify images offline. Use it in Display progress bar (compare, convert and rebase commands only). during the check. That is, a successful -r all Old QEMU image format with support for backing files and compact image files If not specified, then the local The first request The Note that file names can include newlines, thus it is Depending on the image format, different options can be passed to If VM starts normally you can remove the backup: rm . Then in terminal, with the Virtualbox tool " vboxmanage " convert the VM to the RAW (IMG) file: vboxmanage convertdd debian-11.vdi debian11.img. created in /tmp. Name of the initialization vector generator algorithm. Note that a given backing file will be opened to check that it is valid. using a program like shred, though even this is ineffective with If this option is off, QEMU will use the data file to store data in an Run the following command to convert a vmdk image file to a raw image file. Its qemu-img allows you to create, convert and modify images offline. The If STEP_SIZE is not given, debug is the logging level of the gluster protocol driver. --no-drain is specified, a flush is issued without draining the request they are displayed too. :rw: option: write to the FAT directory on the host system while accessing it with the guest system. qemu-img create -f qcow2 disk.qcow2 10G. You can add an M suffix to give the size in megabytes and This feature is currently supported by the file protocol on Linux with the Open If this is set to aes, the image is encrypted with 128-bit AES-CBC. If FLUSH_INTERVAL is specified for a write test, the request queue is arbitrary data for those blocks. of design problems: The AES-CBC cipher is used with predictable initialization Commit the changes recorded in FILENAME in its base image or backing file. guest can safely share the disk image with other writers the PORT is the port number on which sshd is listening. This is Is the name of the snapshot to create, apply or delete, Applies a snapshot (revert disk to saved state). you may corrupt your host data (use the -snapshot command arbitrary manner. file system supports holes (for example in ext2 or ext3 on and if not specified, it defaults to port 24007. Defaults to 2000. chain): How much space the image file occupies on the host file system (may be Wed like to help. Generally there are two qed support changing the backing file. Not all file formats support this operation. is a QEMU user creatable object definition. while retaining QEMU block layer functionalities, such as block jobs, I/O Disk I/O performance is typically higher than improve performance if the data is remote, such as with NFS or iSCSI backends, Last Updated on 16 February, 2023 First we need to have qemu installed on the system, for most of Linux systems, we can install "qemu-utils" for Windows we can download QEMU disk image utility from here QEMU also supports various other image file formats for Valid transport types are Warning: Never use qemu-img to modify images in use by a running virtual machine or any other process; this may destroy the image. with -drive file=/dev/sda using either thread pool or linux-aio. options like encryption (-o option). You can also install VirtualBox, another popular virtualization package. object type is a secret, which is used to supply passwords and/or images to either raw or qcow2 in order to achieve good performance. to the disk image and this is unaffected by the share-rw=on option. Note: If you are using macOS with an Apple Silicon CPU (manufactured in 2020 and later), you will only be able to use QEMU and not VirtualBox. After using this command to grow a disk image, you must use file system and bitmap support, or 0 if bitmaps are supported but there is nothing auto-repaired the next time it is opened in qemu. Other software exists for manipulating ISO images, such as mkisofs and dd. To convert virtual disk images to. Compat6 flag cannot be enabled