[Server data recovery] Data recovery case of server Raid5 array mdisk disk offline

Server Raid Disk Offline Failure:
There are one or more groups of Mdisks in the server, and one hard disk in one group of Mdisks fails and goes offline. The hot spare disk starts and starts to synchronize data.Another hard disk in the group Mdisk is also offline due to a failure, which will cause the synchronization of the hot spare disk to fail, and the Mdisk of the group will fail, making the entire volume unusable.

Server Raid data recovery process:
1. Mirror backup for each disk in the faulty array, all later data recovery work will be performed on the mirror file, without affecting the original diskdata.
2. Analyze and reorganize Mdisk. First, according to the configuration information provided by the user, classify the hard disk according to the Mdisk group.Analyze all hard disks in each group of Mdisks to obtain raid-related information.Virtually reorganize Mdisk using professional data recovery software.
3. Analyze all the information about the pool obtained by Mdisk.Use professional data recovery software to virtually reorganize the pool.
4. Disk analysis.Since raid5 can only allow one member disk to go offline at most, if raid5 crashes, at least two disks fail and go offline.The Beiya data recovery engineer analyzed the underlying data in each member disk and found that the data on the front of the two hard disks was exactly the same. It was initially determined that one of the two hard disks was a hot spare disk, and the other hard disk was a faulty disk.
Based on this, the fault situation can be judged: one of the member disks in raid5 fails and goes offline, and the hot spare disk goes online and starts synchronizing data. At the same time, another member disk also fails and goes offline, and the raid fails.When the raid recovers to normal, because the data on the hard disk that failed first is not up-to-date, some errors occur in the data in the raid after recovery.
5. After analyzing the raid structure of the hard disk and the drop of member disks, use professional data recovery software to complete the formation of Mdisk and pool, and generate the data in them.

Tips: What should I do after a server disk array failure?
1. Don't blindly force online.
The Offline indicator is on, which means that it is required to replace a non-faulty hard disk of the same model and re-calibrate the algorithm.It is very likely that more than one RAID disk array is unstable, and the offline prompt of the server often falsely reports or misses other hard disks that also have hidden dangers.During the forced online process, the hard disk performs a large number of read and write operations. Once other hard disks go offline, data recovery becomes more difficult.Therefore, it is necessary to check the stability of each hard disk before forced online, so as to be more secure.

2. Protect the first site
For manufacturers, hardware equipment repair is the main goal of after-sales service, so data is often sacrificed to repair hardware equipment failures.The engineer of the North Asia Data Recovery Center introduced: The situation that the data is completely destroyed by the user seeking the after-sales service engineer of the manufacturer happens almost every week.Manufacturers' after-sales service engineers tend to repair hardware, while RAID data recovery is mainly based on software operations.In addition, even simple verification operations may bring inconvenience to later data recovery.When the number of damaged RAID hard disks exceeds the fault tolerance capability of the array itself, the mirror image of the damaged hard disk must be completely extracted to complete the final recovery.If the hard disk is powered on frequently, it is easy to cause fatigue damage to the magnetic head, or even scratch the platter.The correct approach should be to consult a professional data recovery service provider immediately.

3. Choose a professional and formal data recovery center
When choosing a data recovery service provider, company size, technical experience, engineer team, and reputation in the industry are all important indicators to consider.