Live Virtual Machine Migration in Fog Computing: State of the Art

Software aging affects the availability of Virtual Machine Monitor (VMM), one of the main components of virtualized environments. Software aging causes internal software degradation due to bugs activation and accumulation during its execution. Software rejuvenation implemented through Virtual Machine (VM) Live Migration may be applied to cope with software aging effects on cloud computing system. Another relevant problem is the power consumption of using software rejuvenation techniques in the virtualized environments. This paper presents availability models based on Stochastic Petri Nets to evaluate two VM Live Migration approaches. These approaches are based on the redundancy schemes: Warm-Standby and Cold-Standby. In the Cold-Standby migration, the migration target machine is started only before the VM Live Migration. In the Warm-Standby Migration, the migration target machine runs along with the source migration machine. Results show that VM Live Migration causes a significant improvement in system availability. Scenarios with a heavy workload present an annual downtime reduction of 164 h. The availability comparison between two approaches reveals that the Cold-Standby approach has a slightly better result due to the decrease in the total number of VM Live Migrations. The power consumption results show that Cold-Standby approach is more efficient in power consumption. In all the observed scenarios, the costs savings by using Cold-Standby approach exceed 40%. The highlights of this paper are: i) a comprehensive model for availability evaluation of cloud computing with VMM rejuvenation through VM migration scheduling; ii) sensitivity analysis to define proper rejuvenation scheduling to maximize system availability and iii) power consumption comparison of the two adopted migration approaches.

High availability is the most important and challenging problem for cloud providers. However, virtual machine monitor (VMM), a crucial component of the cloud infrastructure, has to be frequently updated and restarted to add security patches and new features, undermining high availability. There are two existing live update methods to improve the cloud availability: kernel live patching and Virtual Machine (VM) live migration. However, they both have serious drawbacks that impair their usefulness in the large cloud infrastructure: kernel live patching cannot handle complex changes (e.g., changes to persistent data structures); and VM live migration may incur unacceptably long delays when migrating millions of VMs in the whole cloud, for example, to deploy urgent security patches. In this paper, we propose a new method, VMM live upgrade, that can promptly upgrade the whole VMM (KVM & QEMU) without interrupting customer VMs. Timely upgrade of the VMM is essential to the cloud because it is both the main attack surface of malicious VMs and the component to integrate new features. We have built a VMM live upgrade system called Orthus. Orthus features three key techniques: dual KVM, VM grafting, and device handover. Together, they enable the cloud provider to load an upgraded KVM instance while the original one is running and cut-and-paste'' the VM to this new instance. In addition, Orthus can seamlessly hand over passthrough devices to the new KVM instance without losing any ongoing (DMA) operations. Our evaluation shows that Orthus can reduce the total migration time and downtime by more than $99%$ and $90%$, respectively. We have deployed Orthus in one of the largest cloud infrastructures for a long time. It has become the most effective and indispensable tool in our daily maintenance of hundreds of thousands of servers and millions of VMs.

As Internet of Things (IoT) and Industrial Internet of Things (IIoT) devices are becoming increasingly popular in the era of the Fourth Industrial Revolution, the orchestration and management of numerous fog devices encounter a scalability problem. In fog computing environments, to embrace various types of computation, cloud virtualization technology is widely used. With virtualization technology, IoT and IIoT tasks can be run on virtual machines or containers, which are able to migrate from one machine to another. However, efficient and scalable orchestration of migrations for mobile users and devices in fog computing environments is not an easy task. Naïve or unmanaged migrations may impinge on the reliability of cloud tasks. In this paper, we propose a scalable fog computing orchestration mechanism for reliable cloud task scheduling. The proposed scalable orchestration mechanism considers live migrations of virtual machines and containers for the edge servers to reduce both cloud task failures and suspended time when a device is disconnected due to mobility. The performance evaluation shows that our proposed fog computing orchestration is scalable while preserving the reliability of cloud tasks.

Fog computing is an emerging computing paradigm that has come into consideration for the deployment of Internet of Things (IoT) applications amongst researchers and technology industries over the last few years. Fog is highly distributed and consists of a wide number of autonomous end devices, which contribute to the processing. However, the variety of devices offered across different users are not audited. Hence, the security of Fog devices is a major concern that should come into consideration. Therefore, to provide the necessary security for Fog devices, there is a need to understand what the security concerns are with regards to Fog. All aspects of Fog security, which have not been covered by other literature works, need to be identified and aggregated. On the other hand, privacy preservation for user’s data in Fog devices and application data processed in Fog devices is another concern. To provide the appropriate level of trust and privacy, there is a need to focus on authentication, threats and access control mechanisms as well as privacy protection techniques in Fog computing. In this paper, a survey along with a taxonomy is proposed, which presents an overview of existing security concerns in the context of the Fog computing paradigm. Moreover, the Blockchain-based solutions towards a secure Fog computing environment is presented and various research challenges and directions for future research are discussed.

Virtualization has been shown to be an attractive path to increase overall system resource utilization. The use of live virtual machine (VM) migration has enabled more effective sharing of system resources across multiple physical servers, resulting in an increase in overall performance. Live VM migration can be used to load balance virtualized clusters. To drive live migration, we need to be able to measure the current load imbalance. Further, we also need to accurately predict the resulting load imbalance produced by any migration.In this paper we present a new metric that captures the load of the physical servers and is a function of the resident VMs. This metric will be used to measure load imbalance and construct a load-balancing VM migration framework. The algorithm for balancing the load of virtualized enterprise servers follows a greedy approach, inductively predicting which VM migration will yield the greatest improvement of the imbalance metric in a particular step. We compare our algorithm to the leading commercially available load balancing solution - VMware's Distributed Resource Scheduler (DRS). Our results show that when we are able to accurately measure system imbalance, we can also predict future system state. We find that we can outperform DRS and improve performance up to 5%. Our results show that our approach does not impose additional performance impact and is comparable to the virtual machine monitor overhead.

Virtualization techniques effectively handle the growing demand for computing, storage, and communication resources in large-scale Cloud Data Centers (CDC). It helps to achieve different resource management objectives like load balancing, online system maintenance, proactive fault tolerance, power management, and resource sharing through Virtual Machine (VM) migration. VM migration is a resource-intensive procedure as VM’s continuously demand appropriate CPU cycles, cache memory, memory capacity, and communication bandwidth. Therefore, this process degrades the performance of running applications and adversely affects efficiency of the data centers, particularly when Service Level Agreements (SLA) and critical business objectives are to be met. Live VM migration is frequently used because it allows the availability of application service, while migration is performed. In this paper, we make an exhaustive survey of the literature on live VM migration and analyze the various proposed mechanisms. We first classify the types of Live VM migration (single, multiple and hybrid). Next, we categorize VM migration techniques based on duplication mechanisms (replication, de-duplication, redundancy, and compression) and awareness of context (dependency, soft page, dirty page, and page fault) and evaluate the various Live VM migration techniques. We discuss various performance metrics like application service downtime, total migration time and amount of data transferred. CPU, memory and storage data is transferred during the process of VM migration and we identify the category of data that needs to be transferred in each case. We present a brief discussion on security threats in live VM migration and categories them in three different classes (control plane, data plane, and migration module). We also explain the security requirements and existing solutions to mitigate possible attacks. Specific gaps are identified and the research challenges in improving the performance of live VM migration are highlighted. The significance of this work is that it presents the background of live VM migration techniques and an in depth review which will be helpful for cloud professionals and researchers to further explore the challenges and provide optimal solutions.

CBase: Fast Virtual Machine storage data migration with a new data center structure

Live migration of virtual machines (VMs) can consume excessive time and resources, and may affect application performance significantly if VM memory pages get dirtied faster than their content can be transferred to the destination. Existing approaches to this problem transfer memory content faster with high-speed networks, slow down the dirtying of memory pages by throttling the execution of applications, or reduce the amount of memory content to be transferred, for example, using compression. However, these approaches incur high resource costs or application performance penalties. In this paper, we propose to skip the transfer of VM memory pages that need not be migrated for the execution of running applications at the destination, by exploiting applications' assistance. We have designed a generic framework for application-assisted live migration and then used it to build and evaluate JAVMM, which migrates VMs running various types of Java applications skipping the transfer of garbage in Java memory. Our experimental results show that JAVMM can reduce the completion time, the network traffic of transferring memory pages, and the application downtime of Java VM migration, all by up to over 90%, compared to the vanilla Xen VM migration, without incurring noticeable performance penalty to applications.

Resource allocation in smart settings, more specifically in Internet of Things (IoT) transportation, is challenging due to the complexity and dynamic nature of fog computing. The demands of users may alter over time, necessitating more trustworthy resource allocation and administration. Effective resource allocation and management systems must be designed to accommodate changing user needs. Fog devices don’t just run fog-specific software. Resource and link failures could be brought on by the absence of centralised administration, device autonomy, and wireless communication in the fog environment. Resources must be allocated and managed effectively because the majority of fog devices are battery-powered. Latency-aware IoT applications, such as intelligent transportation, healthcare, and emergency response, are now pervasive as a result of the enormous growth of ubiquitous computing. These services generate a large amount of data, which requires edge processing. The flexibility and services on-demand for the cloud can successfully manage these applications. It’s not always advisable to manage IoT applications exclusively in the cloud, especially for latency-sensitive applications. Thus, fog computing has emerged as a bridge between the cloud and the devices it supports. This is typically how sensors and IoT devices are connected. These neighbouring Fog devices control storage and intermediary computation. In order to improve the Fog environment reliability in IoT-based systems, this paper suggests resource allocation and management strategy. When assigning resources, latency and energy efficiency are taken into account. Users may prioritise cost-effectiveness over speed in a fog. Simulation was performed in the iFogSim2 simulation tool, and performance was compared with one of the existing state-of-the-art strategy. A comparison of results shows that the proposed strategy reduced latency by 10.3% and energy consumption by 21.85% when compared with the existing strategy.

Data compression is usually perceived as a mean to help improve performance of live migration of Virtual Machines (VM). However, such perception may be wrong since there are many factors involved in the combination of live migration and data compression. This paper presents a novel performance model to describe the speedup of VM live migration when used in combination with data compression mechanisms, namely the Amdahl's Law of data compression for live migration of VMs. The speedup is calculated by dividing the total live migration time when the migration is performed in combination with data compression by that without data compression. This model introduces live migration bandwidth as a new factor in the speedup calculation. The live migration bandwidth is the data transmission rate of a live migration mechanism. According to our model, the speedup of live migration using data compression would approach zero as the live migration bandwidth increases toward infinity. A set of theorems derived from the model are presented. A number of experiments have been conducted to confirm these theorems. In the experiments, QEMU-KVM's pre-copy live migration is used to migrate VMs running several memory-intensive OpenMP NAS Parallel benchmarks with and without data compression. Live migrations are performed over 100 Mbps and 1 Gbps networks. Experimental results confirm the validity of the proposed Amdahl's Law of data compression model.

Live migration of virtual machines (VMs) can benefit data centers through load balancing, fault tolerance, energy saving, etc. Although live migration between geographically distributed data centers can enable optimized scheduling of resources in a large area, it remains expensive and difficult to implement. One of the main challenges is transferring the memory state over WAN. There is a conflict between the low data transmission speed over WAN and the rapid change of memory contents. This paper proposes a novel live migration method with page-count-based data deduplication, which takes advantage of the fact that VMs running same or similar operating systems and other software tend to have identical memory pages. Template pages are selected based on number of occurrences of each page across multiple VMs and indexed by content hash. When a memory page is transferred, the source host first compares it with the templates. If a match is identified, the source host transfers the index instead of the data of the memory page. The experimental results show that our approach reduces the migration time by 27% and the data transferred by 38% on average compared to the default method of QEMU-KVM.

Fog computing, which provides low-latency computing services at the network edge, is an enabler for the emerging Internet of Things (IoT) systems. However, due to the limited capacity of the fog devices, a large number of tasks will still be offloaded to the cloud for processing. This can overload the backbone network and cause excessive delays. In addition, the distribution of IoT devices is uneven. This paper groups fog nodes into a fog federation to increase the number of tasks that fog nodes can handle. The boom in fog computing has made fog pricing an important issue. But so far, no one has set a price for the federation. This article uses the Stackelberg model to simulate the interaction process between fog federation and IoT devices. First, fog devices bundle certain computing power, memory, and some other resources into a computing resource block (CRB). Then, fog devices act as a leader to release the price of CRB, and IoT devices act as a follower to determine the amount of CRB purchased. This article introduces how IoT can buy the right amount of CRB to minimize its cost and how CRB is priced to maximize the revenue of the fog federation.KeywordsFog computingCloud computingStackelbergInternet of Things

With the rapid growth of Internet of Things (IoT) applications, the classic centralized cloud computing paradigm faces several challenges such as high latency, low capacity and network failure. To address these challenges, fog computing brings the cloud closer to IoT devices. The fog provides IoT data processing and storage locally at IoT devices instead of sending them to the cloud. In contrast to the cloud, the fog provides services with faster response and greater quality. Therefore, fog computing may be considered the best choice to enable the IoT to provide efficient and secure services for many IoT users. This paper presents the state-of-the-art of fog computing and its integration with the IoT by highlighting the benefits and implementation challenges. This review will also focus on the architecture of the fog and emerging IoT applications that will be improved by using the fog model. Finally, open issues and future research directions regarding fog computing and the IoT are discussed.

With the rapid growth of Internet of Things (IoT) applications, fog computing enables the IoT to provide efficient services by extending the cloud computing paradigm to the edge of the network. However, the existing attribute-based encryption schemes rarely focus on user and attribute revocation in fog computing and most of them still impose high computational and storage overhead on resource-limited IoT devices. In this article, we propose an efficient attribute-based encryption outsourcing scheme with user and attribute revocation for fog-enabled IoT. The proposed scheme improves the existing encryption scheme that uses the concept of attribute groups to achieve attribute revocation, making it suitable for fog computing and improving the efficiency of ciphertext update. In addition, it implements a novel method of user revocation in fog computing based on the characteristics of fog computing. In order to reduce the computing and storage burden of IoT devices, the heavy computation operations of encryption and decryption are outsourced to fog nodes and part of secret keys are stored in fog nodes. The security analysis shows that the proposed scheme is secure under the Decisional Bilinear Diffie–Hellman (DBDH) assumption. The performance analysis shows that the proposed scheme has high revocation efficiency and is efficient enough to be deployed in practical fog computing.

With the continuous evolution of technology, the prevalence of the Internet of Things (IoT) has grown significantly. However, with this rise comesa number of challenges for integrated Cloud Computing (CC), including security, performance, latency, and network issues. Fortunately, Fog Computing is a solution that addresses these concerns by bringing CC closer to IoT devices. Essentially, fog serves as a data hub that processes and stores information locally on the fog node, rather than sending it to a cloud server. This results in faster response times and higher- quality services compared to those offered by traditional cloud servers. Fog Computing can optimize service delivery for multiple IoT clients by allowing the administrationof services and resource provisioning outside of CC, nearer to devices, or at specific locations for Service Level Agreements (SLAs). It's important to note that Fog Computing is not intended to replace CC, but rather to complement itas a critical component. In this paper, we explore various computing paradigms, examine the features and architecture of Fog Computing, analyze its relationship with IoT, and assess differentalgorithms used in Fog Computing systems. Furthermore, we tackle the distinctive challenges that emerge with Fog Computing as an intermediate layer between IoT sensors/devices and data centers. Keywords: Fog Computing, Internet of Things(IOT), Cloud Computing (CC).