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This article mainly introduces the relevant knowledge of what the method of raid data recovery is, the content is detailed and easy to understand, the operation is simple and fast, and has a certain reference value. I believe you will gain something after reading this raid data recovery method. Let's take a look at it.

[introduction to physical servers and logical storage]

The customer uses an IBM 3850 server and a RAID5 disk array made of 4 300GB SAS disks. The server operating system is windows2003 x64, there is a single-node Oracle, version 11.2.0.2, and the data is stored as a file system without archiving. The amount of data in this oracle is small. There is only one user built by the oracle, and the default users tablespace is used. There is only one data file under the users tablespace, which is less than 1GB.

[server failure phenomenon]

Due to heavy load, there is a problem with the underlying RAID disk array. In order to save the data, the user does a series of operations to rebuild RAID, and then aborts RAID initialization due to a disk failure, but a small amount of data is destroyed by synchronization. At this time, the RAID disk array is accessible.

Although there is an error in the system, it can start normally, but the D disk, that is, the partition where the oracle database is located, cannot be opened. The customer can open it normally after chkdsk, but the oracle cannot be started. The customer reinstalled the oracle system on the original disk and imported the previously backed up dmp file, but the data is too poor.

[data recovery process]

After the customer contacted the Beijing data recovery center, the data recovery center arranged for the Oracle data recovery engineer and the server data recovery engineer to come to the customer site for recovery at the same time.

First of all, analyze the RAID layer: rebuilding the RAID will bring the most serious damage, but the analysis shows that the block size and disk order of the reconstructed RAID are the same as the original, but only a small amount of data in the front part is synchronized in the initialization process, the raid layer is not damaged, and the database has not been destroyed.

Then analyze the damage caused by the later administrator to partition chkdsk and reinstall the oracle system and import dmp files: Chkdsk does not destroy the user data area, chkdsk only modifies the file system metadata area. At this time, there is still no damage to the database file, at most, only the MFT or directory entries of the file are destroyed. The most serious thing is to reinstall the Oracle system and import the dmp file, which not only destroys the file system metadata area, but also overwrites the user data area.

The third step is to analyze the NTFS file system of disk D: it is found that the MFT of all the original oracle data files is overwritten, and the NTFS log is also overwritten by reincarnation, and the unavailable information is found from the NTFS metadata area. You can only use the Oracle recovery program within the data recovery center to restore the entire partition. After scanning, it is found that the Oracle instance is ANSORA, and an original complete control file and an original complete undotbs tablespace data file are scanned, and the important system and users tablespace data files are destroyed to varying degrees.

Among them, the data file of system tablespace is only 10MB in the middle and back, which should be about 700MB, while the data file of users tablespace is also partially overwritten, but only 4MB.

Extract and find the data, the next step is to repair the seriously damaged database.

Because the system tablespace is not available, the data dictionary cannot be obtained. After communicating with the customer, the customer confirms three important tables, which are also large. The structure of the three tables is obtained from the database returned by the customer imp, and the corresponding segment is found from the data file that recovers the users tablespace. But there is a table that cannot be matched, and the customer is asked again. The customer said that this table had changed the field. Then build a new table structure corresponding to the segment in the users tablespace data file, and then extract the data of the three tables through the official dul tool of oracle. After customer verification, the data has no problem.

[data recovery result] it took three days, and more than 99% of the data specified by the user was successfully restored.

This is the end of the article on "what is the method of raid data recovery?" Thank you for reading! I believe that everyone has a certain understanding of the knowledge of "what is the method of raid data recovery". If you want to learn more knowledge, you are welcome to follow the industry information channel.

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