Shulou(Shulou.com)06/02 Report--

Based on recent research on the use of Proxmox VE and previous experience with XenServer, in this article, I will discuss Proxmox VE and XenServer and analyze and compare the two most popular open source hypervisors. This analysis focuses on the hypervisor advantages in virtual machine resource allocation, supported virtualization methods, server architecture, and number of virtual machines. Operating system compatibility and management functions of host and client. These two open source hypervisors are popular around the world because they provide an enterprise-class user experience similar to VMware products. The promotion and use of open source-based hypervisor changes the way enterprise managers manage their computing resources, reduces the operating costs of IT, and improves performance and flexibility. Although there are many excellent open source products such as ZStack available in China and the user experience is not lower than the above two products, but in terms of enterprise functional openness, it can not be compared with it, so it is not included in the comparison scope of this article.

Hypervisor is the main carrier and core of virtualization technology adoption and investment. At present, there are a wide range of open source virtualization kernels in the market, such as Xen, KVM, LXC, Docker and so on. These virtualized cores all rely on a single server hardware and system. In the case of large-scale operation, virtual machine management program is needed to manage, orchestrate and pool hardware cluster resources. Therefore, the capacity, compatibility, user experience and performance of hypervisors are critical to solve the management challenges of operators in using virtualization technology. In this respect, the open source hypervisor OpenStack has been very unfriendly, so open source virtualization hypervisors developed specifically for these pain points are very popular; in addition, although the growth of virtualization technology has brought a significant drop in prices, the use of open source virtualization hypervisors can further reduce IT investment and operating costs. Therefore, after the big waves, simple and practical, close to users Proxmox VE and XenServer has become the most popular open source virtualization manager.

L Proxmox VE (English: Proxmox Virtual Environment, often referred to as Proxmox) is an open source-based virtualization solution that provides computing, networking, and storage functions in a software package. Proxmox VE is a virtualization platform that can run both virtual machines and containers. Proxmox VE is based on Debian Linux development and is completely open source. For flexibility, Proxmox VE supports two virtualization technologies: KVM virtual machines and LXC containers.

L XenServer is an open source virtualization platform based on the open source Xen project, which was acquired by Citrix, renamed XenServer, and continued to open source after being commercialized for a period of time. XenServer is mainly based on Xen open source virtualization kernel to build virtualization management stack. After teaming with Citrix products and endorsing AWS cloud computing products based on Xen, it is widely used in the production environment of major enterprises.

From the perspective of today's mature and stable open source virtualization management programs, the above two open source virtualization management products with a long history, stable version iteration and various production environment practices are the most outstanding. And these two products also show high similarity in many aspects, so analysis and comparison can objectively provide more detailed comparative analysis. to ensure that in the cost savings and the implementation of industry solutions based on virtualization technology, the adopter can match the best virtualization management program. And implement the optimal solution based on its own considerations such as virtualization requirements, organizational size, personnel skills and computing workload.

In terms of the classification of virtualization technologies, Proxmox VE and XenServer support different virtualization methods, such as full virtualization, paravirtualization, operating system virtualization and hardware-assisted virtualization. Specifically, Proxmox VE supports full virtualization, hardware-assisted virtualization (KVM-based) and operating system virtualization, but XenServer supports full virtualization, paravirtualization and hardware-assisted virtualization, as shown in Table 1 below.

Table 1: virtualization hypervisor and virtualization methods

In the case of XenServer, although hardware virtualized virtual machines need Intel-based VT-x or AMD-V-based x86 CPU to run hardware-assisted virtualization, paravirtualization does not require the functional support of processor virtualization, but modifies the guest operating system kernel, which is different in the implementation of Proxmox VE (KVM). Unlike XenServer, Proxmox VE supports operating system-level virtualization, which is not common for type 1 virtualization hypervisors. Most type 1-based virtualization hypervisors on the market today support paravirtualization and hardware-assisted virtualization, while full virtualization does not perform well because binary translation is involved during operation, mainly because binary conversion is time-consuming and can lead to high performance overhead. The main solution today is to use alternative caching to improve binary translation to increase the speed of binary translation, but this may increase the cost of memory usage. Paravirtualization overcomes the performance problem of full virtualization, and paravirtualization on x86 architecture can provide 80% to 97% performance of hosts. This is because under the implementation mechanism of paravirtualization technology, the operating system can recognize the super invocation commands sent by the virtualization manager. Therefore, the advantage of XenServer supporting paravirtualization is that the Linux-based operating system running on XenServer can get great performance, but because the paravirtualization needs to modify the operating system kernel, the paravirtualization approach does not support Microsoft's Windows operating system.

It is gratifying that both Proxmox VE and XenServer support hardware-assisted virtualization, and through hardware-assisted virtualization, both Proxmox VE and XenServer can provide appropriate operational performance. Hardware-assisted virtualization can offload the virtualized part of the software to the hardware and execute it through hardware-designed circuits, and the execution efficiency is much higher than the computing power based on CPU processor / memory virtualization combination. The most typical example is AWS's Nitro, where network, storage, security management and monitoring are decoupled from traditional virtual machines and migrated to proprietary hardware in Nitro system architecture. These functions will be modular and micro-service, so that they can migrate quickly and evolve according to new requirements at any time. The Nitro system uses customized ASIC, and the virtualization methods implemented by the previous software are implemented through customized ASIC hardware. The advantage of this architecture is that we can allocate all server resources to customers' virtual machines or containers, and each major IO module can run at the same high speed as the hardware.

With the operation and progress of open source hardware OCP and Scorpio projects, I think virtualization hypervisors like Proxmox VE and XenServer can also achieve standardized decoupling of networking, storage, security management and monitoring to proprietary modular hardware. But this is not our focus today. Under the architecture of today's common hardware, open source virtualization management programs meet the principles of utility and ease of use, which is the most valuable solution of modern virtualization-driven IT solutions.

The main virtual body of virtualization technology is our hardware CPU, memory and IO.

First of all, from the point of view of the supported CPU architecture, both Proxmox VE and XenServer only support CPU of x86 / 64, but not CPU of Power and other architectures. Although from the perspective of virtualization kernel Xen and KVM, Xen and KVM are adapted to CPU of Power and other architectures, and even CPU and Zhongke of domestic Godson and other MIPS architectures are adapted, these two virtualization managers are not integrated and adapted for painstaking efforts.

Table 2 shows a summary of the correspondence between the virtualization hypervisor and the CPU architecture.

Table 2: virtualization hypervisor and CPU architecture

Secondly, on the supported client operating systems, by reading the official compatibility list, we can find that the compatibility difference between Proxmox VE and XenServer for client operations lies in the compatibility of the Unix system. The details are as follows:

Table 3: virtualization hypervisor and client operating system

In this regard, Proxmox VE is the only open source-based type 1 hypervisor that works efficiently with all guest operating systems. Unlike Proxmox VE, XenServer does not support FreeBSD,NetBSD or any other BSD variants as guest operating systems, but users can try to install them as HVM guests and install operating systems such as FreeBSD themselves, but because I / O is simulated, its performance does not match that of other semi-virtual clients. BSD systems such as FreeBSD have a special virtualization manager, bhyve, for which you are interested to know, and are currently looking for compatibility support for other operating systems of the X86-64 architecture.

"in terms of the number of supported virtual machines, because the parameter performance of each version is different, a comparison is made with newer versions of two hypervisors, such as Proxmox VE 5.x and XenServer 7.x." The number of virtual machines supported by the hypervisor is an important indicator to evaluate its processing power and memory characteristics for resource allocation and server integration. Table 4 summarizes the number of virtual machines supported by Proxmox VE and XenServer hypervisors.

Table 4:VM quantity, CPU and RAM features

The maximum number of clients in XenServer 7 is 500, but for Linux-based clients, this number can increase to 650, but the number of such tests can vary with acceptable performance baselines, such as running more for lower-configured virtual machines. Proxmox VE has similar load dynamics. On the vCPU support of virtual machines, XenServer supports adding up to 32 vCPU per virtual machine. For resource balancing between VCPU, XenServer uses a fair sharing balancing algorithm to ensure that CPU resources are allocated among virtual machines to balance the load on physical CPU resources accordingly. In addition, XenServer can dynamically allocate physical processors to any specific virtual machine, which allows virtual machines to make effective use of available CPU resources when available. One of the benefits of XenServer is that it can use different types of CPU in the same resource pool, that is, it supports heterogeneous resource pools. Typically, XenServer uses FlexMigration and Extended Migration technologies for Intel and AMD to run heterogeneous environments, respectively. For Proxmox VE, the number of vCPU that can be supported per virtual machine is 160. The maximum 192GB memory space can be allocated to a single guest virtual machine. Both support dynamic memory control and hot plug of CPU, memory, network and hard disk.

In terms of network functions, for virtual network interface cards (NIC), the maximum number of NIC that XenServer can assign to each virtual machine is 7. However, there are changes based on guest operating systems, and some operating systems support more virtual network cards. And in the XenServer physical host, the maximum number of physical network cards supported is 16. For Proxmox VE, because it is built on the Debian system, the number of network cards supported far exceeds this limit. Both Proxmox VE and XenServer use Linux Braidge and Open vSwitch to provide fair network I / O resources and QoS control between VM. In terms of network function, XenServer is a little more powerful than Proxmox V, but the powerful part is based on the commercial version. From the comparison of the open source version, the network management functions of the two products are the same. In Proxmox VE, each node can support up to 4094 bridges with a common naming format of vmbrX, where X represents an integer between 0 and 4094. One of the advantages of Proxmox VE is that the conditions for real-time migration between nodes are less than XenServer.

In the case of virtual disk I / O, the maximum number of virtual disk drives that XenServer can assign to VM is 16, but this may vary depending on the type of guest operating system. Disk I / O resources split between VM are done using a fair sharing method based on the defined set priority. XenServer uses the Storage Manager, which is built-in support for file-and block-based storage types. "for Proxmox VE, supported storage includes directories that meet local storage, logical volume management (LVM) for local or shared iSCSI targets, network file system (NFS) for (OmniOS,FreeNAS,Ubuntu, etc.), Gluster file system (GlusterFS), and Ceph." Proxmox uses FreeNAS for backup purposes. Although NFS sharing is the most commonly used VM backup scenario, you can also use local and Ceph FS for full backups.

Finally, the two management programs are compared in terms of management functions. The management functions in the hypervisor are important for easily creating and managing virtual machines. Some management features include asset management, configuration snapshots, high availability, live migration, maintenance mode, performance metrics, storage migration, virtual machine cloning, VM migration, capacity planning / management, virtual firewall, virtual machine backup / recovery, thin configuration, storage multipathing, performance reporting, automatic discovery, failover, and multiple host resource pools. Table 5 shows the different management features supported by the Proxmox VE and XenServer hypervisors.

Table 5: management functions of the virtualization hypervisor

As you can see from Table 5 above both hypervisors provide similar management functions which means that there is no significant difference between the two hypervisors. However, there are significant differences in how these features work and produce the expected results. For example, both XenServer and Proxmox VE support graphical user interface (GUI) and command line interface (CLI) management. However, XenServer is a GUI client based on the CS architecture, which protects all communication with the XenServer host through the GUI client installed in the Windows environment and by using 256bit SSL (AES) encryption. On the other hand, Proxmox VE uses the Web GUI client based on HTML5 to realize the graphic interface operation access of Proxmox VE. Both have proprietary CLI management command tools. Another management function that is different is the cloning of virtual machines. Both XenServer and Proxmox VE support full and attached clones. The difference is that the storage file formats of the two are different, and the cloning capabilities of the virtual machines supported are different. In addition, in the use of storage space, XenServer supports streamlined provisioning of existing virtual machines on the local disk in the format of EXT3 and NFS repositories, and Proxmox VE is related to the supported format because of the use of KVM kernel. For virtual firewalls, both hypervisors have management capabilities that enhance security through internal packet filtering and monitoring. From a security perspective, XenServer consists of a control domain (Dom0), which is a secure privileged virtual machine that runs XAPI (management tool stack) that can be used to control virtual machine lifecycle operations in network, storage, authentication, and computing resource management. Proxmox VE uses role-based user and rights management to monitor virtual machines and containers, storage pools, and host nodes. In addition, Proxmox VE uses Linux PAM or LDAP to apply user authentication. The two hypervisors also provide live migration, high availability (HA), virtual machine snapshots, and performance reporting. These are the excellent functions that the enterprise can greatly help the business operation in the process of operation.

In addition, XenServer does better than Proxmox VE in import, export and migration from virtual machines. Basically, XenServer supports the import and export of virtual machines in homogeneous and heterogeneous environments, and supports the industry-standard Open Virtualization format (OVF), so it can accept all virtual machines created from other hypervisors, including proprietary hypervisors such as VMware and Hyper-V. This is mainly achieved using XenServer Conversion Manager. Proxmox VE does not develop a special GUI import and export tool, but supports virtual machines in qcow2, raw and vmdk formats, and its import and export function needs to be realized through the CLI tool.

The storage supported by qcow2 is NFS and directory, and the Raw format supports LVM,RBD,iSCSI and directory. Vmdk supports NFS and directories. Due to high I / O overhead and low processing speed, the qcow2 format is not suitable for data-intensive virtual machines, such as database servers. However, qcow2 files are useful when there are budget constraints and limited storage space. This image type supports KVM live snapshots to preserve the VM state. The original image type ensures performance because VM is faster because it has direct pass-through access. The original file format can only provide fixed-size or densely configured VM images, so it is the preferred file format for all Proxmox VM. The virtual drives that can be added to Proxmox are IDE (3), SATA (5), VirtIO (15), and SCSI (13). The original disk image files are always pre-allocated, so there is a risk of overconfiguration beyond the total available storage space. Another advantage of this image type is that it supports KVM live snapshots. With regard to the vmdk image format, Proxmox uses it only to facilitate VM migration to other hypervisors. The existence of the vmdk file format allows Proxmox files to swim in a heterogeneous hypervisor environment.

Proxmox VE and XenServer are similar in many ways, but the main difference is that XenServer does not support Linux containers (operating system virtualization), while Proxmox VE does. Compared with XenServer, this feature increases the strength of Proxmox VE. Although Proxmox VE uses a unique virtualized API, fully virtualized with KVM and operating system virtualization based on LXC containers, it runs and manages well without using the Libvirt interface in a production environment. Both Proxmox VE and XenServer are popular hypervisors that require a high level of operating system and virtualization skills to securely manage virtual machines throughout their lifecycle. According to the size and requirements of the adoption organization, how to allocate and share resources among virtual machines is the main role of the virtualization hypervisor. Therefore, Proxmox VE and XenServer are the most valuable and feasible solutions for virtualized server infrastructure for organizations that aim to reduce costs with the highest performance.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.