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Vsan is a scalable distributed storage architecture based on vSphere kernel. Vsan builds vsan storage layer by installing flash memory and hard disk in vSphere cluster host. These devices are controlled and managed by vsan, and vsan forms a unified shared storage layer for vSphere cluster.

VSphere provides HA function to ensure that the business can run on other hosts after the failure of a single host. The same data of the same virtual machine must be saved on different hosts, and host failures are also allowed. However, if multiple hosts fail at the same time, it will cause the entire vsan storage to crash. Generally, sudden power outage or abnormal shutdown will lead to virtual machine failure. Here is how to recover the virtual machine failure caused by abnormal shutdown.

The failure environment is a set of VMWARE VSAN super-converged infrastructure with three server nodes. Each server node is equipped with 2 SSD hard drives with 200G capacity and 4 mechanical hard drives with 1T capacity, a total of 6 SSD hard drives and 12 mechanical hard drives.

Two disk groups are created on each server node, each disk group uses 1 SSD hard disk as cache disk, 2 mechanical hard disks as capacity disk, and a total of 6 disk groups are configured to form VSAN storage space to store virtual machine files.

In the course of use, due to abnormal shutdown, the logical architecture in VSAN fails, and some virtual machine disk components have problems, resulting in the loss of disk files.

one。 Disk mirroring and fault detection

In order to prevent the irreducible modification of the original disk caused by some operations in the process of data recovery, resulting in secondary data loss, the original disk is mirrored and backed up.

Remove all the hard disk numbers from the node server of VSAN, connect them to the backup server, and use WinHex software to make a byte-by-byte mirror backup of all hard drives.

Get the underlying images of all the hard drives on the customer's three-node servers, with a total of 18 image files.

After analyzing and scanning all the mirror files, it is found that the metadata and component information of the failed virtual machine is not seriously damaged or lost, it is relatively complete, and there is great confidence that it can be completely restored.

two。 Recovery plan 1, scan component information.

Because all files in VSAN exist as objects, and each object will be divided into multiple components, scan all component information, and record information such as component ID and ID of which object the component belongs to. Write a program to scan component information.

2. Extract components.

According to the information in the component, find each data block and the logical position of the block in the component, and write a program to extract the complete component.

3. Merge VMDK files.

According to the description information in the component information, the components are combined according to the RAID level recorded in the description information and the logical position of each component in the object, and the complete object, that is, the complete vmdk file, is spliced.

4. Refresh cache disk data.

Each component may have part of the data left on the cache disk and not written to the capacity disk, and the program will refresh the data on the cache disk to the corresponding component or object.

5. Merge snapshots.

For vmdk files with snapshots, merge the snapshot with the parent disk.

6. Parse vmdk and restore files.

Parse the merged vmdk file and extract the backup file of the SQL server 2008 R2 database.

7. Database restore and detection.

Install the SQL server 2008 R2 database and restore the backup files of the extracted database. There is no error in the restore process. After the successful restore, use the dbcc command to check the integrity of the database and check that there are no errors.

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