A Virtual Storage Environment for SSDs and HDDs in Xen Hypervisor

Transcription

1 A Virtual Storage Environment for SSDs and HDDs in Xen Hypervisor Yu-Jhang Cai*,Chih-kai Kang+, and Chin-Hsien Wu* *National Taiwan University of Science and Technology +Research Center for Information Technology Innovation Academia Sinica

2 Outline Introduction Motivation Related Work System Design and Architecture Implementation Experiment Conclusion

3 Introduction Nowadays, virtualization is a popular technology to provide an abstract hardware emulation due to the increasing hardware speed and capabilities. Advantages of virtualization technology: Merge physical servers, reduce the space required for the servers. Enhance resource utilization. Simplify the management of the servers. Conserve energy to reduce carbon emission.

4 Introduction Three parts of Xen: Xen Hypervisor Domain 0 Domain U

5 Introduction Xen Hyperviosr An abstraction layer between the guest domains and the physical hardware. Allocating and controlling resources.

6 Introduction Domain 0 A modified Linux kernel and is only one privileged virtual machine. Directly access the hardware resources, and contain drivers for the hardware resources.

7 Introduction Domain U A general virtual machine, since domain U is a unprivileged virtual machine. Sending I/O requests through front-end driver, and backend driver in domain 0 will handle and perform the I/O requests.

8 Introduction Characteristics of SSDs (Solid-State Drives) No mechanical latency Low power consumption Shock resistance Provide better performance than HDDs (Hard-Disk Drives), especially for a lot of random accesses Smaller storage capacity and more expensive than HDDs

9 Introduction Storage devices combine SSDs and HDDs Regard SSDs as a secondary-level cache. Regard SSDs as a storage device. Virtual Storage Virtual Storage SSDs Mapping Table HDDs HDDs SSDs

10 Motivation When some (soft real-time) applications in virtual machines require high I/O performance, SSDs (solid-state drives) can be used because of its better performance than traditional HDDs (hard-disk drives) in terms of read and write accesses. Therefore, we will build a virtual storage environment for SSDs and HDDs in Xen hypervisor. We believe that the proposed method can provide users a platform to include various storages such as SSDs (i.e., fast access) and HDDs (i.e., low cost).

11 Related Work [1]Chai-Hao Tsai, Jerry Chou, Yeh-Ching Chung, Value-Based Tiering Management on Heterogeneous Block-Level Storage System, IEEE 4th International Conference on Cloud Computing Technology and Science, Propose data migration algorithms based on the performance of difference access patterns on each type of storage devices. They regard SSDs as storage space and storage cache of HDDs.

12 Related Work [2]Youngjae Kim, Aayush Gupta, Bhuvan Urgaonkar, Piotr Berman, and Anand Sivasubramaniam, HybridStore A Cost-Efficient, High-Performance Storage System Combining SSDs and HDDs, 19th Annual IEEE International Symposium on Modelling, Analysis, and Simulation of Computer and Telecommunication Systems, They formulate some constraints (such capacity, performance, and lifetime) as a Mixed Integer Program to decide which storage to store. But they do not consider data migration in different storage devices.

13 Related Work [3]Hannes Payer, Marco A.A. Sanvido,Zvonimir Z. Bandic and Christoph M. Kirsch, Combo Drive: Optimizing Cost and Performance in a Heterogeneous Storage Device, WISH, Combine SSDs and HDDs into a single heterogeneous storage device. Move some files to SSDs/HDDs based on file type. SSD:.exe,.dll,.sys,.msi,.cab,.drv,.jar, HDD:.jpg,.pdf,.wmv,.wma,.mp3,.doc,.xls, Need to modify file systems Virtual Address Low Logical Address Logical Address high SSD HDD

14 A Virtual Storage Environment for SSDs and HDDs in Xen Hypervisor Blktap in the kernel space Can not directly access physical storage devices. Receives all I/O requests of Domain U. Transfers the I/O requests to Blktap in the user space of Domain 0 to perform I/O requests to physical storage devices.

15 A Virtual Storage Environment for SSDs and HDDs in Xen Hypervisor Blktap in the user space Provide Xen hypervisor an interface to access physical storage devices.

16 A Virtual Storage Environment for SSDs and HDDs in Xen Hypervisor I/O Requests from Multiple Virtual Machines to Physical Storage Devices Monitor Play an important role for dynamic and adaptive adjustment in I/O performance Content mapping table Record which data are transferred to SSDs or HDDs

17 Implementation Mainly modify two components in Blktap driver: Tap-disk Block-aio

18 Implementation Receive and analyze I/O requests (Tap-disk) Tap-disk is a process which can handle I/O requests and provide an interface for virtual machine management. We can modify Tap-disk to analyze the I/O requests and then determine their storage destinations (i.e., the monitor mechanism). According to the analysis of I/O requests, we can transfer appropriate I/O requests to suitable SSDs to improve overall I/O performance. Component File Function Functionality Tap-disk Tapdisk-vbd.c tapdisk_vbd_create() tapdisk_vbd_issue_request() counter content mapping table() monitor() 1. Create and maintain a content mapping table 2. Create a monitor mechanism 3. Analyze I/O requests 4. Deliver I/O requests and its locations to Blockaio component Note that a policy in the monitor to determine which data should be placed in SSDs or HDDs for dynamic adjustment in I/O performance can be found in [4].

19 Implementation Perform I/O requests to physical storage devices (Block-aio) Block-aio component is a process to handle each virtual machine image such as image open/close and I/O requests to the image. Block-aio is a bottom layer of Xen hypervisor to access physical storage devices. We modify Block-aio to perform I/O requests to the final storage devices (e.g., SSDs or HDDs). Component File Function Functionality Block-aio Block-aio.c tdaio_open() tdaio_complete() tdaio_queue_read() tdaio_queue_write() 1. Maintain virtual machine images in SSDs and HDDs 2. Perform I/O requests to SSDs and HDDs 3. Migrate data between SSDs and HDDs

20 Experimental Evaluation Hardware Environment Configuration CPU Hard Disk Drive Solid-state Drive Memory Intel(R) Core(TM) i7 CPU 3.07GHz Hitachi HDS721010CLA332 1TB SSD Intel 320 series 160GB 8GB System Domain 0 Virtualization Software Xen Linux Kernel Linux Operating System Ubuntu Memory 2GB Operating System Ubuntu Domain U Memory Storage space 128MB 32GB vcpu 1

21 Experimental Evaluation I/O traces file Web search OLTP Read 99% Read 25% Write 1% Write 75% Request size 8kB Request size 512B~2kB Workload Size 16.7GB Workload Size 7.2GB Total Read 65.8GB Total Read 5.2GB Total Write 8MB Total Write 28GB

22 Experimental Evaluation Web search result Intel SSDs was about 11 times faster than Hitachi HDD when running one virtual machine. When running two or more virtual machines, Intel SSD was about 20 times faster than Hitachi HDD.

23 Experimental Evaluation Web search result Intel SSDs was about 2.2 and 2 times faster than 50% HDD and 50% SSD when running one/two and three virtual machines, respectively. Intel SSDs was about 1.7 times faster than 50% HDD and 50% SSD when running four virtual machines.

24 Experimental Evaluation Financial results (OLTP) Intel SSD was about 10 times faster than Hitachi HDD when running one virtual machine. When running two and more virtual machines, Intel SSD was about 18 and 22 times faster than Hitachi HDD, respectively.

25 Experimental Evaluation Financial results (OLTP) Intel SSD was about 1.3 times faster than 50% HDD and 50% SSD in all situations.

26 Conclusion We build a virtual storage environment for SSDs and HDDs in Xen hypervisor. The proposed virtual storage environment using SSDs and HDDs can not only provide better performance than only HDDs but also provide a more economical solution than only SSDs.

27 Reference [1]Chai-Hao Tsai, Jerry Chou, Yeh-Ching Chung, Value-Based Tiering Management on Heterogeneous Block-Level Storage System, IEEE 4th International Conference on Cloud Computing Technology and Science, [2]Youngjae Kim, Aayush Gupta, Bhuvan Urgaonkar, Piotr Berman, and Anand Sivasubramaniam, HybridStore A Cost-Efficient, High- Performance Storage System Combining SSDs and HDDs, 19th Annual IEEE International Symposium on Modelling, Analysis, and Simulation of Computer and Telecommunication Systems, [3]Hannes Payer, Marco A.A. Sanvido,Zvonimir Z. Bandic and Christoph M. Kirsch, Combo Drive: Optimizing Cost and Performance in a Heterogeneous Storage Device, WISH, [4]Chih-Kai Kang, Yu-Jhang Cai, Chin-Hsien Wu and Pi-Cheng Hsiu, A Hybrid Storage Access Framework for Virtual Machines, accepted and will appear in IEEE RTCSA, 2013.

28 Thank you! Q & A