qcow
Sign in to saveAlso known as QEMU Copy-on-Write, QCOW1 disk image
qcow is a file format for disk image files used by QEMU, a hosted virtual machine monitor. It stands for "QEMU Copy On Write" and uses a disk storage optimization strategy that delays allocation of storage until it is actually needed. Files in qcow format can contain a variety of disk images which are generally associated with specific guest operating systems. Two versions of the format exist: qcow and qcow2 which use the .qcow and .qcow2 file extensions, respectively. An intermediate development version was called qcow3, but all results were integrated into qcow2, so this name never became an
~2 min read
Encyclopedic overview
3 sectionsContents
- Features
- qcow2
- References
qcow is a file format for disk image files used by QEMU, a hosted virtual machine monitor. It stands for "QEMU Copy On Write" and uses a disk storage optimization strategy that delays allocation of storage until it is actually needed. Files in qcow format can contain a variety of disk images which are generally associated with specific guest operating systems. Two versions of the format exist: qcow and qcow2 which use the .qcow and .qcow2 file extensions, respectively. An intermediate development version was called qcow3, but all results were integrated into qcow2, so this name never became an official new format.
qemu-img command allows to inspect, check, create, convert, resize and take snapshot of qcow images. The e2fsprogs command e2image also has support for generating qcow2 files to avoid the use of sparse file support.
Excerpted from Wikipedia’s “qcow” article, available under the CC BY-SA 4.0 licence.