Failures are normal rather than exceptional in the cloud computing environments. To improve system avai- lability, replicating the popular data to multiple suitable locations is an advisable choice, as users can acces...Failures are normal rather than exceptional in the cloud computing environments. To improve system avai- lability, replicating the popular data to multiple suitable locations is an advisable choice, as users can access the data from a nearby site. This is, however, not the case for replicas which must have a fixed number of copies on several locations. How to decide a reasonable number and right locations for replicas has become a challenge in the cloud computing. In this paper, a dynamic data replication strategy is put forward with a brief survey of replication strategy suitable for distributed computing environments. It includes： 1） analyzing and modeling the relationship between system availability and the number of replicas; 2） evaluating and identifying the popular data and triggering a replication operation when the popularity data passes a dynamic threshold; 3） calculating a suitable number of copies to meet a reasonable system byte effective rate requirement and placing replicas among data nodes in a balanced way; 4） designing the dynamic data replication algorithm in a cloud. Experimental results demonstrate the efficiency and effectiveness of the improved system brought by the proposed strategy in a cloud.展开更多
Human enterovirus 71(EV71)is the main causative pathogen of hand,foot,and mouth disease(HFMD)in children.The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades,and no vaccine and effe...Human enterovirus 71(EV71)is the main causative pathogen of hand,foot,and mouth disease(HFMD)in children.The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades,and no vaccine and effective antiviral medicine are available.Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections.In this study,we demonstrated that curcumin showed potent antiviral effect again EV71.In Vero cells infected with EV71,the addition of curcumin significantly suppressed the synthesis of viral RNA,the expression of viral protein,and the overall production of viral progeny.Similar with the previous reports,curcumin reduced the production of ROS induced by viral infection.However,the antioxidant property of curcumin did not contribute to its antiviral activity,since N-acetyl-L-cysteine,the potent antioxidant failed to suppress viral replication.This study also showed that extracellular signal-regulated kinase(ERK)was activated by either viral infection or curcumin treatment,but the activated ERK did not interfere with the antiviral effect of curcumin,indicating ERK is not involved in the antiviral mechanism of curcumin.Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin–proteasome system(UPS),we found that curcumin had no impact on UPS in control cells.However,curcumin did reduce the activity of proteasomes which was increased by viral infection.In addition,the accumulation of the short-lived proteins,p53 and p21,was increased by the treatment of curcumin in EV71-infected cells.We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB,both of which are required for the formation of viral replication complex.We found that curcumin significantly reduced the level of both proteins.Moreover,the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication.We also demonstrated that curcumin showed anti-apoptotic展开更多
The use of technology has increased vastly and today computer systems are interconnected via different communication medium. The use of distributed systems in our day to day activities has solely improved with data di...The use of technology has increased vastly and today computer systems are interconnected via different communication medium. The use of distributed systems in our day to day activities has solely improved with data distributions. This is because distributed systems enable nodes to organise and allow their resources to be used among the connected systems or devices that make people to be integrated with geographically distributed computing facilities. The distributed systems may lead to lack of service availability due to multiple system failures on multiple failure points. This article highlights the different fault tolerance mechanism in distributed systems used to prevent multiple system failures on multiple failure points by considering replication, high redundancy and high availability of the distributed services.展开更多
The bane of achieving a scalable distributed file sharing system is the centralized data system and single server oriented file [sharing] system. In this paper, the solution to the problems in a distributed environmen...The bane of achieving a scalable distributed file sharing system is the centralized data system and single server oriented file [sharing] system. In this paper, the solution to the problems in a distributed environment is presented. Thus, inability to upload sizeable files, slow transportation of files, weak security and lack of fault tolerance are the major problems in the existing system. Hence, the utmost need is to build a client-server network that runs on two or more server systems in order to implement scalability, such that when one server is down, the other(s) would still hold up the activities within the network. And to achieve this reliable network environment, LINUX network operating system is recommended among others as a preferred platform for the synchronization of the server systems, such that every user activity like sending of internal memos/mails, publication of academic articles, is replicated;thereby, achieving the proposed result. Hence, Scalable Distributed File Sharing System provides the robustness required to having a reliable intranet.展开更多
Distributed key value storage systems are among the most important types of distributed storage systems currently deployed in data centers. Nowadays, enterprise data centers are facing growing pressure in reducing the...Distributed key value storage systems are among the most important types of distributed storage systems currently deployed in data centers. Nowadays, enterprise data centers are facing growing pressure in reducing their power consumption. In this paper, we propose GreenCHT, a reliable power management scheme for consistent hashing based distributed key value storage systems. It consists of a multi-tier replication scheme, a reliable distributed log store, and a predictive power mode scheduler （PMS）. Instead of randomly placing replicas of each object on a number of nodes in the consistent hash ring, we arrange the replicas of objects on nonoverlapping tiers of nodes in the ring. This allows the system to fall in various power modes by powering down subsets of servers while not violating data availability. The predictive PMS predicts workloads and adapts to load fluctuation. It cooperates with the multi-tier replication strategy to provide power proportionality for the system. To ensure that the reliability of the system is maintained when replicas are powered down, we distribute the writes to standby replicas to active servers, which ensures failure tolerance of the system. GreenCHT is implemented based on Sheepdog, a distributed key value storage system that uses consistent hashing as an underlying distributed hash table. By replaying 12 typical real workload traces collected from Microsoft, the evaluation results show that GreenCHT can provide significant power savings while maintaining a desired performance. We observe that GreenCHT can reduce power consumption by up to 35%-61%.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos. 61070162, 71071028 and 70931001the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant Nos. 20110042110024 and 20100042110025the Fundamental Research Funds for the Central Universities of China under Grant Nos. N100604012, N090504003 and N090504006
文摘Failures are normal rather than exceptional in the cloud computing environments. To improve system avai- lability, replicating the popular data to multiple suitable locations is an advisable choice, as users can access the data from a nearby site. This is, however, not the case for replicas which must have a fixed number of copies on several locations. How to decide a reasonable number and right locations for replicas has become a challenge in the cloud computing. In this paper, a dynamic data replication strategy is put forward with a brief survey of replication strategy suitable for distributed computing environments. It includes： 1） analyzing and modeling the relationship between system availability and the number of replicas; 2） evaluating and identifying the popular data and triggering a replication operation when the popularity data passes a dynamic threshold; 3） calculating a suitable number of copies to meet a reasonable system byte effective rate requirement and placing replicas among data nodes in a balanced way; 4） designing the dynamic data replication algorithm in a cloud. Experimental results demonstrate the efficiency and effectiveness of the improved system brought by the proposed strategy in a cloud.
基金This work was supported by the grants of National Natural Science Foundation of China to Zhaohua Zhong(Grant No.81271825)Wenran Zhao(Grant No.31270198).
文摘Human enterovirus 71(EV71)is the main causative pathogen of hand,foot,and mouth disease(HFMD)in children.The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades,and no vaccine and effective antiviral medicine are available.Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections.In this study,we demonstrated that curcumin showed potent antiviral effect again EV71.In Vero cells infected with EV71,the addition of curcumin significantly suppressed the synthesis of viral RNA,the expression of viral protein,and the overall production of viral progeny.Similar with the previous reports,curcumin reduced the production of ROS induced by viral infection.However,the antioxidant property of curcumin did not contribute to its antiviral activity,since N-acetyl-L-cysteine,the potent antioxidant failed to suppress viral replication.This study also showed that extracellular signal-regulated kinase(ERK)was activated by either viral infection or curcumin treatment,but the activated ERK did not interfere with the antiviral effect of curcumin,indicating ERK is not involved in the antiviral mechanism of curcumin.Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin–proteasome system(UPS),we found that curcumin had no impact on UPS in control cells.However,curcumin did reduce the activity of proteasomes which was increased by viral infection.In addition,the accumulation of the short-lived proteins,p53 and p21,was increased by the treatment of curcumin in EV71-infected cells.We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB,both of which are required for the formation of viral replication complex.We found that curcumin significantly reduced the level of both proteins.Moreover,the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication.We also demonstrated that curcumin showed anti-apoptotic
文摘The use of technology has increased vastly and today computer systems are interconnected via different communication medium. The use of distributed systems in our day to day activities has solely improved with data distributions. This is because distributed systems enable nodes to organise and allow their resources to be used among the connected systems or devices that make people to be integrated with geographically distributed computing facilities. The distributed systems may lead to lack of service availability due to multiple system failures on multiple failure points. This article highlights the different fault tolerance mechanism in distributed systems used to prevent multiple system failures on multiple failure points by considering replication, high redundancy and high availability of the distributed services.
文摘The bane of achieving a scalable distributed file sharing system is the centralized data system and single server oriented file [sharing] system. In this paper, the solution to the problems in a distributed environment is presented. Thus, inability to upload sizeable files, slow transportation of files, weak security and lack of fault tolerance are the major problems in the existing system. Hence, the utmost need is to build a client-server network that runs on two or more server systems in order to implement scalability, such that when one server is down, the other(s) would still hold up the activities within the network. And to achieve this reliable network environment, LINUX network operating system is recommended among others as a preferred platform for the synchronization of the server systems, such that every user activity like sending of internal memos/mails, publication of academic articles, is replicated;thereby, achieving the proposed result. Hence, Scalable Distributed File Sharing System provides the robustness required to having a reliable intranet.
文摘Distributed key value storage systems are among the most important types of distributed storage systems currently deployed in data centers. Nowadays, enterprise data centers are facing growing pressure in reducing their power consumption. In this paper, we propose GreenCHT, a reliable power management scheme for consistent hashing based distributed key value storage systems. It consists of a multi-tier replication scheme, a reliable distributed log store, and a predictive power mode scheduler （PMS）. Instead of randomly placing replicas of each object on a number of nodes in the consistent hash ring, we arrange the replicas of objects on nonoverlapping tiers of nodes in the ring. This allows the system to fall in various power modes by powering down subsets of servers while not violating data availability. The predictive PMS predicts workloads and adapts to load fluctuation. It cooperates with the multi-tier replication strategy to provide power proportionality for the system. To ensure that the reliability of the system is maintained when replicas are powered down, we distribute the writes to standby replicas to active servers, which ensures failure tolerance of the system. GreenCHT is implemented based on Sheepdog, a distributed key value storage system that uses consistent hashing as an underlying distributed hash table. By replaying 12 typical real workload traces collected from Microsoft, the evaluation results show that GreenCHT can provide significant power savings while maintaining a desired performance. We observe that GreenCHT can reduce power consumption by up to 35%-61%.
