September 13-16, 2022
Dublin, Ireland + Virtual
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Friday, September 16 • 16:50 - 17:30
Dm-qcow2: qcow2 as Device-mapper Block Device - Aleksandr Mikhalitsyn & Denis V. Lunev, Virtuozzo

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Most of container runtimes provides containers rootfs using host fs bindmounts, layered fs (overlayfs, aufs) or using a loop device. OpenVZ 7 uses special custom format ploop (Parallels loop) which more feature-rich and allows IO freeze, snapshots, backups. On the VM planet there is QCOW2 format. A new dm-qcow2 driver [1] developed by Kirill Tkhai (Virtuozzo) allows to utilize this format for the containers. This talk will cover main topic parts briefly: Intro and motivation. - Why loop is not ideal for the system containers? - Why in the kernel? - Why device mapper? - How it works on practice? (Example or demo) Tech details - Generic design. How IO requests are handled - Application to snapshots/backups Discussion - Integration with LXC? - Performance benefits for Qemu (vhost integration) [1] dm: Introduce dm-qcow2 driver to attach QCOW2 files as block device https://lore.kernel.org/all/164846619932.251310.3668540533992131988.stgit@pro/#r


Denis Lunev

Core Team Lead, Virtuozzo
Denis Lunev is working in Virtuozzo around 20 years dealing with various aspects of virtualization, both in virtual machine and container worlds. Right now is working on QEMU/KVM optimizations.
avatar for Aleksandr Mikhalitsyn

Aleksandr Mikhalitsyn

Software Developer, Virtuozzo
Working on the Linux kernel and CRIU project at Virtuozzo

Friday September 16, 2022 16:50 - 17:30 IST
Wicklow Hall 1 (Level 2)
  ContainerCon, Container Images and Registries