【Server hardware configuration】
Huawei OceanStor S5600T server, MD1200 disk cabinet, raid5 disk array group, 50T capacity.
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【Upper configuration situation】
The upper layer of the server is allocated a lun, linux operating system, and two partitions. Partition one is expanded by lvm, and partition two is formatted as an xfs file system.
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[Server failure situation]
The operation error of reinstalling the system on the server causes the disk partition to change. The second partition in the original server is inaccessible due to unknown reasons, and the data in the partition is lost.
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[Backup server data]
Before the data recovery operation, in order to prevent the data analysis operation from destroying the original situation of the data, the server data recovery engineer uses a data recovery tool to perform a mirror backup of all the disks in the client server. After the backup is completed, the original server disk is restored to the server, and the mirror disk is connected to a dedicated data recovery device for data recovery analysis.
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[Data recovery process]
1. Use the mirror disk to analyze the raid disk sequence, stripe size and other information;
2. Virtually reorganize the raid structure;
3. Locate the partition starting position of the
xfs file system ; 4. Verify the integrity and correctness of the xfs file system sex;
5, repair xfs file system superblock structure; 
the repair is completed superblock
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6, xfs file system directory entries and missing node repair; 
repair of complete root
Redo directory entry
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7, programming resolve xfs file system after the repair is completed, extract the data.
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【Data Recovery Results】
After analyzing the xfs file system of the client server, the analysis result is that the super block at the head of the file system is lost, some directory items in the file system are lost, and some nodes are lost. According to the super block backup and the directory tree structure in the file system, the super block is repaired and restored. After repairing and rebuilding the lost nodes and directory items, more than 99% of the data in the file system can be completely restored to the 
repaired directory structure
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[Complete recovery of server data]
Since the customer did not write any destructive operations on the storage after the data was lost, most of the data and file system information remains intact, and the data is almost 100% recovered.