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Vinchin Blog Introduction to VMware virtualization storage principle and data recovery method

Introduction to VMware virtualization storage principle and data recovery method


Virtual machine technology is one of the types of virtualization technology, the virtualization technology is turning things from one form into another form, the most commonly used in the operating system virtualization technologies have the memory of virtualization, the actual runtime memory space to meet the needs of users may be far greater than the physical memory size of the machine, using virtualization technology of memory, virtual memory, users can be part of the hard disk which is transparent to the user. For example, virtual private networks (VPNS) can be used to virtualize a secure, stable "tunnel" in a public network, so that users feel as if they are using a private network. Virtualization technology seems to be a more secure way of data storage, but there is no 100% secure storage mode in the world. Once the underlying server hosting the virtual machine or storage fails or even the hard disk of the server fails, the upper virtual machine may become unavailable and the data in the virtual machine will be lost.

What is the nature of a snapshot that requires a virtual machine to restore; Assume that the virtual machine for data recovery was migrated to ESXI from a physical server three years ago, and a snapshot was taken after the successful migration. A total of 26 virtual machines were run on the ESXI, and the underlying storage device was a server of a certain brand. One day, the staff accidentally performed a restore snapshot operation, which means that the data in the virtual machine is restored to the state when the migration was just 3 years ago, and the data of the last 3 years is in the deleted state.

Restoring a snapshot is essentially the same as deleting data. The virtual machine removes the snapshot and releases the underlying storage space to the appropriate location, then reuses that space to store new data. This means that if a virtual machine accidentally restores a snapshot, all virtual machines on the storage should be moved or migrated to another ESXI as soon as possible.

Introduced data recovery method before that need to introduce the underlying structure of VMFS file system, VMFS file system is VMware virtualization has its own file system, in this file system all disk is divided into several regions by default, these areas are the smallest units called a block, each the size of the block is 1 MB, is made up of 1024 block, each for a MAP, this information is recorded in the file system of a particular area. The sequence of blocks in each map is not continuous on the hard drive in the house but all the blocks in each map must belong to the same file.

Another feature of the Vmfs file system also helps to restore virtual machine data. In the VMFS file system, if a file is deleted, the index entry of the file is deleted at the underlying data level. The actual data content and only the data map are not actually deleted. We are required for data recovery for the whole of the inside of the file system all free map is extracted, and then find a snapshot file header structure map can be according to the file structure continues to extract the remaining pieces, after completion of all data extraction combined with the original VMDK synthesis a new VMDK, finally, the new mount up and into the VMDK files, explain the data inside the virtual machine is completed data recovery.

Anyway, Vinchin Backup & Recovery supports VMware's virtualization. It can backup virtual machines in a standalone ESXi host, or in a host under the vCenter cluster environment. It is specially designed for SMBs who have the ability to build their own virtual environment, but willing to pay less money on protecting their VMs.

  • Tag:
  • Virtualization

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