KVM virtual machine image Production Test

1. Conclusion The differential generation of virtual machines using backup images can quickly generate a large number of virtual machines and save disk space, which is of great significance in the production environment. After testing, the read Pressure on the backup image is very small, and the system pressure is mainly due to the write pressure on the poor image. In order to achieve good results, backup images and differential images should be distributed to different physical hard disks, and the image security should be ensured. 2. backup image differential Generation Virtual Machine (backing_file) function indicates that the backup image differential Generation Virtual Machine means that multiple virtual machines share a backup image. Each virtual machine can read the image as needed, for write operations, write your own image file, similar to the snapshot copy on write mechanism. Backup images can be in raw and qcow2 formats, while differential images can only be in qcow2 format.
Www.2cto.com 3. advantages of using the difference: 1) quickly generate a virtual machine image, and generate a virtual machine image instantly using a command. 2) saves disk space. Multiple VMS share one backup image, saving a lot of space. 4. risks of using the differential mode 1) when multiple virtual machines are started, the I/O pressure is very high, especially during the first startup. 2) The backup image has high security requirements. 5. test environment hardware Lenovo R510G7cpu Intel (R) Xeon (R) CPU E5506 @ 2.13GHz memory 8G hard drive sas 146Gx2 raid0 x2 software centos 6.3 kernel 2.6.32-279.19.1.el6.x86 _ 64
Www.2cto.com 6. run the-B command to generate a differential image. The-B parameter indicates the backup image. If the generated image and the backup image are not in the same directory, use the absolute path. Otherwise, the virtual machine cannot be started. Qemu-img create-f qcow2/datapool/w2k3-test-04-B/data/win2003ent32chs test, write a script, without stopping the generation of poor image, start the virtual machine, 5 minutes later, shut down the virtual machine, delete the virtual machine, and generate an image. Use the cacti monitoring platform to view the disk's io pressure. 7. Test Result 1) Size of the occupied space after the first startup of different operating systems

System space Windows server 200344 MWindows server 200885MCentos5. 618MCentos6. 211 M 2) the pressure test places the backup image and differential image in the same hard disk or raid group, and finds that the disk read/write io is very high, and several windows server 2003 virtual machines are started at the same time, the blue screen is displayed when the third virtual machine is started. This test method does not test the read/write pressure of the specific backup image and differential image. Therefore, the backup image and differential image are separated to different raid groups for testing.
In www.2cto.com Windows server 2003, when a virtual machine is repeatedly deleted, generated, and started, the system's io pressure is generated. Datavg-datapool is the lv for storing differential images. We can see that the writing pressure is very high, and data-images is the lv for storing backup images. We can see that the main pressure is the read pressure, which is very small, less than one iops. I/O pressure on the system during repeated deletion, generation, and startup of ten virtual machines on Windows server 2003. Datavg-datapool is the lv for storing images with different sizes. It can be seen that the write pressure is very high, with an average of over 600 iops and a maximum of over 5000 iops. data-images is the lv for storing backup images. We can see that the main pressure is the read pressure, which is very small and less than 3 iops. 3) the destructive test simulates the scenario where the backup image is damaged. The running Virtual Machine will not crash immediately, and a blue screen will appear during the startup of the virtual machine that has not been started.
Www.2cto.com 8. convert the difference image into a common image, use qemu-img convert conversion difference w2k3-test-01 for a common image w2k3-test-01-10, format for qcow2qemu-img convert-f qcow2-O qcow2 w2k3-test-01 w2k3-test-01-10qemu-img info w2k3-test-01image: w2k3-test-01file format: qcow2virtual size: 8.0G (8589934592 bytes) disk size: 122Mcluster_size: 65536 backing file:/data/win2003ent32chsqemu-img info w2k3-test-01-10image: w2k3-test-01-10file format: qcow2virtual size: 8.0G (8589934592 bytes) disk size: 3.20.cluster _ size: 65536
Www.2cto.com 9. changing the backup image-u parameter is not a safe method. However, changing the backup image without the parameter-u will compare the difference between the old backup image and the new backup image, qemu-img rebase-u-B w2k3-test-01-10 w2k3-test-01qemu-img info w2k3-test-01image: w2k3-test-01file format: qcow2virtual size: 8.0G (8589934592 bytes) disk size: 122Mcluster_size: 65536 backing file: w2k3-test-01-10