New: Pavmkvm801qcow2
qemu-img create -f qcow2 -o preallocation=metadata pavmkvm801.qcow2 100G
virt-install --name pavmkvm801 --ram 4096 --vcpus 2
--disk pavmkvm801.qcow2 --cdrom /iso/ubuntu.iso
--graphics spice --network default
Let's examine the technical specifications that distinguish this release.
| Feature | Specification in "new" version |
| :--- | :--- |
| Format | qcow2 |
| Cluster Size | 64 KB (optimal for SSDs and NVMe) |
| Preallocation | Metadata only (falloc) – balances speed vs. disk usage |
| Compression | zstd (Zstandard) level 3 – replacing legacy gzip for 70% faster decompression |
| Compatibility | QEMU 6.0+ required; libvirt 7.0+ recommended |
| Encryption | AES-256 (LUKS based) optionally pre-configured via qemu-img |
| Virtual Size | 80 GB (sparse, actual usage typically 8-12 GB) |
If your virtual machines experience any of the following, the answer is a resounding yes: pavmkvm801qcow2 new
The pavmkvm801qcow2 new format is not just an incremental patch; it is a fundamental rethinking of how virtual disk images handle modern storage hardware. By embracing dynamic clusters, asynchronous discards, and faster snapshots, it brings KVM storage performance to within striking distance of raw device passthrough—while retaining all the flexibility of qcow2.
Decide on size (e.g., 20G).
Location example: /var/lib/libvirt/images/pavmkvm801.qcow2
qemu-img create -f qcow2 /var/lib/libvirt/images/pavmkvm801.qcow2 20G
Verify:
qemu-img info /var/lib/libvirt/images/pavmkvm801.qcow2
Output will show:
file format: qcow2
virtual size: 20 GiB
disk size: 196 KiB (initially small, grows with usage)
Previous iterations used gzip for compress qcow2 clusters. The pavmkvm801qcow2 new image is optionally compressed with zstd. This reduces the download size by approximately 15% compared to gzip at the same compression level, but more importantly, it decompresses 4x faster, allowing for rapid VM instantiation.
“Permission denied” on image – fix ownership: virt-install --name pavmkvm801 --ram 4096 --vcpus 2 --disk
sudo chown libvirt-qemu:kvm /var/lib/libvirt/images/pavmkvm801.qcow2
VM won’t start – no space on host – check:
df -h /var/lib/libvirt/images
Corrupted qcow2 – try repair:
qemu-img check -r all pavmkvm801.qcow2