Off-line data recovery case of two hard drives in the disk array:

One of the customer’s servers caused a red light on a hard drive for unknown reasons, but the server is still operating normally and the administrator did not take any action. Then the server Another hard disk in the same alarm prompt appeared, and the server crashed. The data recovery engineer restores the disk array data as follows (the following operations are risky, please backup before operating):
1. Start the server, and manually enter the management program during the server self-check to check the raid disk array situation and find the hard disk The status is Failel. Manually reset one of the offline hard disks to the online status and try to restart the server but the restart fails.
2. Re-Fail the hard disk, repeat the last operation steps to put another hard disk online, start the server, the server starts successfully.
3. Check whether the database data in the system and the server are running normally, and then use the array configuration tool to manually rebuild the failed disks. After the rebuild is completed, the server and raid disk array system will be restored to their original state.

The second case of offline data recovery from two hard drives in the disk array:

In this case, the server that needs data recovery is a 2850 model of a certain brand. There is a raid5 disk array with 6 hard disks in the server. The hard disks in the array are SCSI hard disks with a single disk capacity of 300G. The server operating system is linux Redhat4; the file system is an ext3 file system. During the normal use of the server, two hard disks were offline due to unknown reasons. The administrator used the method mentioned in Case 1 to force one of the hard disks to go online. However, after trying to find that the server’s operating system started abnormally, and the data could not be recovered by forced online, so I contacted the North Asia Data Recovery Center for professional server data recovery operations. The data recovery engineer performs a complete sector-level backup of the client server. During the backup process, it was discovered that a hard disk in the server that is not offline has a large number of bad sectors. It may be that the server has not read the bad sectors of the hard disk, so it has not been offline. . After the backup work is completed, the raid array structure is analyzed and the raid environment is reorganized to verify the raid structure, and the damaged structure is corrected and archived manually. Finally, embed the corrected and archived data on a normal server array for data verification. In the server data recovery work, we encountered a large number of faults in which two hard disks of the raid5 disk array were offline at the same time. In fact, the raid5 array supports redundancy protection when one hard disk is offline. A group of raid5 arrays will not cause the server to be paralyzed when one hard disk is offline, but if two or more hard disks are offline, the server will be in a paralyzed state. And it cannot go online automatically. Due to the sensitivity of the raid controller, most hard drives are disconnected only due to random reasons such as power fluctuations and controller bugs, so there may be no serious physical failures of the dropped disks. This is the case. But at this time, the administrator’s forced online operation is very risky. Once the online error occurs, the controller will cause some irreversible damage to the data. When the administrator enters the operating system, the file system is inconsistent to repair, and all hard disks in the server are repaired. Data is inconsistent, and data recovery is very difficult.