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Server hard disk offline forced online data loss how to recover?

2025-01-19 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Servers >

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Server failure description:

Customers use Dell 2850 server to build a raid5 disk array, which contains 6 hard disks (SCSI hard disk, single disk capacity 300G), and the server operating system is linux Redhat4; file system and ext3 file system. The server was paralyzed in the process of use, and the administrator checked the array and found that two hard drives were offline and one of them was forced to go online, but the operating system started abnormally. At this time, the administrator realized the seriousness of the matter, immediately shut down the server, and then contacted the data recovery center for data recovery.

Conclusion of initial inspection of data recovery center:

In the server data recovery work, it is very common for two raid5 hard drives to go offline. Because the raid5 disk array supports the honor protection of one hard disk offline, once multiple hard drives are offline, the server will be paralyzed and will not go online automatically. As the raid controller has a certain surface sensitivity, most of the hard disk drop is closely due to power fluctuations, controller bug and other random reasons, so the disconnect disk may not have serious physical failure. This is the case. But at this time, the risk of forced online operation by the administrator is very great, once the online error will cause the controller to produce some irreversible damage to the data, and when the administrator enters the operating system, it will be repaired because the file system is inconsistent, all the hard disk data in the server is inconsistent, and the data recovery is very difficult.

Server data recovery process:

First of all, make a full backup of all the hard drives in the server, and during the backup process, it is found that several hard drives have bad paths but are not offline, because raid did not read the bad paths of the hard drives. After the backup is completed, the raid structure of the original server is analyzed, and then the raid environment is simulated to verify the raid structure malformation. the structure destroyed in the later stage of the server is manually modified, and the modified data is exported to an intermediate storage for temporary storage. The last step of data recovery is to use the intact hard disk to build a new raid5 disk array on the server and migrate the recovered data to the new raid. Verify that all the recovered data is normal and the data is recovered successfully.

Server data recovery conclusion:

Once multiple hard drives are offline and the server is paralyzed in the raid5 disk array, don't force the online operation blindly. If there is enough spare space, you can mirror all the source hard drives. There are two ways (under WINDOWS2003 or DOS, other operating systems are at risk):

1. You can use the hard disk that is the same or larger than the capacity of the source disk as the target disk, and CLONE all sectors of the source disk to the target disk. Do the same operation on all disks.

2. Each source disk can completely output files to a mass storage space in sector mode (such as high-capacity hard disk, NAS, SAN, DAS, etc.)

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