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KVM vs LXD: What are the differences?
Introduction This Markdown code provides a comparison between KVM and LXD, highlighting their key differences.
Hypervisor Type: KVM is a full virtualization hypervisor that emulates the entire hardware stack, including the processor, memory, and input/output devices, allowing the running of a wide range of operating systems. On the other hand, LXD is a lightweight container hypervisor that utilizes Linux containers to isolate processes and resources, providing lightweight virtualization without the need for emulating hardware.
Resource Overhead: KVM involves higher resource overhead as it requires emulating the complete hardware environment, resulting in higher memory and processing requirements. In contrast, LXD has lower resource overhead as it uses lightweight containers, enabling more efficient utilization of resources and better overall performance.
Isolation Level: KVM provides stronger isolation between virtual machines (VMs) as each VM has its own emulated hardware stack and runs an independent operating system. In contrast, LXD offers a lower level of isolation as it relies on Linux containers, where processes share the same host kernel, making them more lightweight but potentially less secure if the kernel is compromised.
Application Scope: KVM is well-suited for running diverse workloads that require running multiple operating systems concurrently, including legacy systems and platforms. On the other hand, LXD is specifically designed for running Linux containers, making it ideal for applications that require lightweight virtualization and resource efficiency, such as microservices architectures and cloud-native applications.
Manageability and Flexibility: KVM provides more flexibility in terms of customization and configuration options, allowing fine-grained control over virtual machine settings. Additionally, KVM can be managed using various management tools and orchestration platforms. Conversely, LXD focuses on simplicity and ease of use, providing a more straightforward way to manage containers and offering a standardized API for container management.
Migration and Live Snapshots: KVM supports live migration, allowing VMs to be moved between physical hosts without downtime. It also supports live snapshots, enabling the creation of point-in-time backups of running VMs. In contrast, LXD does not natively support live migration, as it mainly focuses on container management rather than VM migration. However, LXD provides similar functionality through the use of container migration and checkpoint/restore mechanisms.
In Summary, KVM is a full virtualization hypervisor suited for running diverse workloads with higher resource overhead, while LXD is a lightweight container hypervisor ideal for Linux containers, providing lower resource overhead and simplicity in management.
lxd/lxc and Docker aren't congruent so this comparison needs a more detailed look; but in short I can say: the lxd-integrated administration of storage including zfs with its snapshot capabilities as well as the system container (multi-process) approach of lxc vs. the limited single-process container approach of Docker is the main reason I chose lxd over Docker.
Pros of KVM
- No license issues4
- Very fast2
- Flexible network options2
Pros of LXD
- More simple10
- Open Source8
- API8
- Best8
- Cluster7
- Multiprocess isolation (not single)5
- Fast5
- I like the goal of the LXD and found it to work great5
- Full OS isolation4
- Container3
- More stateful than docker3
- Systemctl compatibility2