I. Overview
Virtualization backup technology was first provided and initiated by VMware. With the popularization of virtualization applications in enterprises and various industries, mainstream backup software (such as CommVault, etc.) all support VMware, Hyper-V, FusionSphere, Citrix and Xen-based. Or backup of virtualization software derived from KVM. Currently, there are many backup software designed specifically for virtualization (virtual application or virtualized desktop VMware View, MicroSoft VDI, XenDesktop), such as Veeam, eBackup, Avamar and Netvault vRanger.
Regarding the virtual machine backup function, just like the virtual machine snapshot, it exists as a basic function of data protection in many virtualization software. However, when the virtualized backup function performs backup, it will affect business performance, and the backup strategy and networking are not flexible. Therefore, for virtualized backup, the common backup method is to use professional backup software.
VMware introduced the VMware Consolidation Backup backup tool at Infrastructure 3, which provides a set of easy-to-use drivers and backup script interface tools for virtual machines for backup software to call. This set of tools needs to be installed on the backup proxy server (VCB proxy server, support installation In the Windows operating system), back up the supported virtual machines or virtual desktops.
Two, VMware backup interface and principle
In VMware ESXi 4 and above, for the VMFS and NFS disk formats, the VADP API backup interface has been supported. Through this open interface form, mainstream backup software development is adapted and integrated. Currently, mainstream backup software that supports virtual machine backup supports VADP. Realize the backup and recovery of VMs without affecting the VMs of users. VADP's CBT (Changed Block Tracking) feature allows VMware VMkernel to remember which data has been updated since the last snapshot, thereby natively supporting incremental backup of virtual machines.
The backup process is first initiated by the backup management server and connected to the ESX host where the virtual machine needs to be backed up to obtain information about the virtual machine. The backup agent VSA informs the ESX host to create a backup snapshot of the backup target virtual machine. The snapshot is a view of the virtual machine state and data at a certain point in time. The virtual machine can continue to run, but the data on the snapshot is static.
The backup server accesses the virtual disk and snapshot files, backs up the data (used disk data and configuration files) to the backup media, and finally informs the ESX host to delete the backup snapshot. The above figure merges the backup software agent VSA, backup management server and media server, which will be described in detail below.
VADP provides a backup solution that eliminates the need to install a backup client in the business VM. Its data backup has three modes, namely SAN, Hot-add and NBD (Network Block Device). This is based on the backup software agent VSA to obtain the VMs backup list and The data is classified in different ways.
In the SAN backup mode, the backup data directly reads the snapshot backup from the storage through the SAN network, and does not need to go through the LAN. It belongs to the LAN Free backup networking mode. It is required that the backup server can directly read the disk storage of the virtual machine through the SAN (FC / iSCSI). VSA and MA can be deployed independently or together on physical servers. The physical MA server can be connected to the tape library, complete Auxcopy and deduplication and compression functions.
When the production storage supports IntelliSnap (hardware snapshot), the ESXi Proxy and the physical MA can access the LUN where the Data Store is located. The ESX Proxy notifies the virtual machine to complete the storage hardware snapshot. The snapshot is mounted to the VSA (temporary datastore). Snapshot), MA extracts the backup list and backup data through the SAN network, and directly reads the data backup from the storage. The backup data does not pass through the production ESXi and belongs to the Server Free backup networking.
When the production storage does not support hardware snapshots, the physical MA (using physical machines) and VSA can access the LUN where the Data Store is located through the SAN, and obtain the backup VMs list and change data through the VSA (virtual machine software snapshot based on CBT technology) , Backup via SAN network.
In Hot-add backup mode, the VSA backup agent is installed in the virtual machine of the ESXi server that needs to be backed up, so that the backup agent can directly read the backup data in ESXi. VSA and MA can be virtualized deployment (MA can not access the library, low performance, can support deduplication), or VSA virtual deployment, MA physical deployment. The backup agent VSA obtains the snapshot list directly in the hot-add mode, and backs up to the backup medium through the MA in the manner of LAN Base.
If the production storage supports hardware snapshot (IntelliSnap), the ESX Proxy can access the LUN where the Data Store is located. The ESX Proxy notifies the storage to complete the hardware snapshot and mounts it to the VSA as a temporary datastore. The MA extracts the backup list and backup data through the LAN network. For business ESXi servers, it belongs to Server Free backup networking.
In NBD backup mode, the backup agent reads the backup data through the TCP / IP network. VSA and MA can be virtualized deployment (MA can not access the library, low performance, can support deduplication), or VSA virtual deployment, MA physical deployment. The backup agents VSA and MA back up data to the backup medium in the manner of LAN Base. It belongs to the LAN Base network.
In the VMware environment, not all scenarios can be backed up by VADP interface. Like the original raw device mapping (RDM) method, you need to treat the virtual machine as a physical machine and install an iDA agent for backup.
In addition, when backing up based on VADP, virtual machines, applications, and data are backed up together. If you only back up applications and data, you also need to treat the virtual machine as a physical machine.
Three, Hyper-V backup interface and principle
Hyper-V also provides Windows-based VSS service to simplify virtual machine backup. Currently, backup software that supports Hyper-V virtualization includes NBU, Simpana, Veeam and other software. But today is also discussed with Simpana. In the Hyper-V environment, DataStor storage methods mainly include CIFS and CSV. CSV (Cluster Shared Volume) is a cluster file system based on the NTFS file system and the Windows Failover Cluster cluster mechanism, which is commonly used in SAN networking.
VSS Volume Shadow Service is a data protection architecture introduced by Microsoft, which can cooperate with backup software to complete snapshot and data consistency protection. Simpana provides unified management of virtual machine clusters on multiple nodes of Hyper-V, which can more accurately create virtual machine protection strategies according to business needs.
First, you must install a VSA backup agent on each Hyper-V server to obtain backup information and the VMs directory to be backed up. Then, under the scheduling of the backup server, perform virtual machine data backup through the MA media server. For Windows applications in Hyper-V virtual machines, Simpana combines Hyper-V's VSS interface to install VSA backup agents on Hyper-V physical servers, which can back up VMs and application data; but for non-Windows applications in virtual machines For non-Windows systems, you need to treat the virtual machine as a physical machine and install an iDA agent for backup.
Hyper-V also provides hardware VSS function to realize the integration with hardware snapshot (IntelliSnap). The backup management server calls the hardware snapshot of the main storage array through the VSS architecture to implement Server Free networking backup. At present, Hyper-V is not compatible with IntelliSnap storage through VSS in backup scenarios. NetApp's FAS series is one of them.
Windows' VSS service architecture is more widely used than VMware's VADP. In storage consistency data protection and backup scenarios, VSS can provide good data consistency protection for Windows applications. Moreover, many storage vendors such as HP Recovery manager, NetApp SnapManager, etc., integrates this feature in storage management software to achieve snapshot protection for applications such as SQL, Exchange, and VMware.
Four, Citrix backup interface and principle
For backup software, Citrix XenServer also provides a backup-optimized API, but compared to VMware and Hyper-V, the capabilities of the Citrix Xen API are relatively weak.
XenServer is a virtualization system built on the underlying hardware platform. A collection of multiple Xen Servers forms a cluster, and the shared underlying storage is called Xen Pool.
For Simpana backup software, the backup proxy VSA needs to be installed in the Xen virtual machine with Xen Pool storage, and the MA media server needs to be deployed on a separate physical machine or the MA should be installed in the virtual machine. The backup agent VSA interacts with the Citrix Xen API to obtain the backup virtual machine list information, and backs up the data to the media through the MA.
Note: This article is reproduced by the Architect Technical Alliance, and is slightly modified.
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