Real case: Abnormal power outage causes the virtual machine to fail to start recovery success

Source: Internet
Author: User
Virtual machine Data Recovery failure:

The failed storage device is a branded storage EVA8400 model, due to an unexpected power outage in the storage room, a VMware virtual machine in the store could not be started (the Oracle database is stored in the virtual machine), the administrator emptied the cache and attempted to restart the virtual machine but failed. Data recovery is required for the virtual machine that cannot be started.

Virtual machine Data recovery process: 1) merging virtual machine snapshots

Since the snapshot of the VMware virtual machine is that the snapshot file for the virtual machine is created, the subsequent data update occurs only within the snapshot file, and the virtual machine exists with two snapshot files. So the first step in this virtual machine data recovery is to merge two virtual machine snapshots before you can analyze the virtual machine's snapshot files to determine the actual corruption of the virtual disk's internal files.

Virtual machine Data recovery process: 2) Analysis of virtual machine files

Data Recovery engineer After merging two snapshot files, the virtual machine's image file is opened in disk format for analysis, the data inside the file system is very confusing: the original file is lost, the internal part of the file is replaced, and some data is zeroed out. The most evident is that the MySQL database MyISAM index file myi is completely replaced with other data, the file written by date has 10 days of data are all replaced. From the point of view of data recovery because the 10 days of data is still in the buffer is not written to the disk, storage due to an unexpected power outage and restart the process will be emptied buffer, so the initial estimate of the virtual machine in this section of the overwritten data can not be recovered.

Virtual machine Data Recovery process: 3) recovering virtual machine data

MySQL's MyISAM engine uses a separate table space for the data storage of each table, so the data recovery engineer to parse the underlying data, get to the table data, because the index file myi damage degree, the data of this recovery is about 90%. After the customer acceptance data approved the virtual machine data recovery results, data recovery success.

Real case: Abnormal power outage causes the virtual machine to fail to start recovery success

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