[Data Recovery failure description]
A Linux Web server, DELL R200, manages about 50 websites, using a single SATA 160GB HDD. A sudden outage in normal use, the attempt to start again failed to remove the hard drive detects the presence of about 100 bad sectors.
After a data recovery company repaired the bad path, it tried for about 3 days and did not recover successfully.
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[Data recovery failure reason inference]
The cause of the failure of data recovery is often unclear, and this example simply infers the following:
1. After a bad word, the user may attempt to perform an automatic or manual fsck operation, leading to further disaster.
2, the partial block group is all 0 looks, may have done unfinished mkfs.
3, send repair data recovery company is not professional, there is the possibility of destroying data.
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[Data recovery process]
The pc3k with de is first performed to perform a full mirroring operation on the fault disk, and the data is analyzed in the mirror. The entire hard drive consists of two partitions: the boot partition of the 100M and/or partition of the remaining space (through LVM Management), the file system is EXT3. The root partition super block is normal, according to the Super Block view the first Group description table is OK, but the node area is all 0.
Analysis of other block groups based on block Group description table shows that the first 27 block groups are all 0, but the data area before and after the block group obviously has user data. Intermediate Block group metadata is normal (description table, node, bitmap, etc.), and the metadata area of the last block group is all 0.
Try to find the root directory, root directory as a clue, restore the root node area.
The file system tree is generated with the generated root node area and root record, and a large amount of data can be seen after success, and the file system structure is normal. However, some files or folders node is 0, through the node tracking, found that the node area is located in the front and back part of the file system.
Attempting to restore files and folders with a node area of 0, most of the folders are successfully restored, but most of the files cannot be recovered.
Trying to restore what the user has done. TAR. GZ Backup package, restore success, but open prompt error, intermediate data is destroyed, only limited export some sites.
Final data recovery is successful.
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[suggestion to the user]
1, important data must not use a single disk storage environment, the current framework of a simple raid does not require a lot of input.
2, must do a good job of backup, at least, the backup package should not be placed on the same storage body, back and seek the next, also must not put in the same partition.
3, hard disk failure, must not repeatedly try to deal with, should be done as soon as possible full backup operation.
4, as far as possible to choose a professional data recovery company to deal with, not professional companies or individuals will inadvertently or intentionally damage the failure disk (intended to increase the price of the threat or maintain a reputation).
Linux server outage, data loss how to recover data
