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This article introduces the relevant knowledge of "the method of linux server data recovery". Many people will encounter such a dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

[reason for server data recovery]

There are many cases of server data loss, and it is usually impossible to identify the causes of server data loss. The common reasons for loss are: server hard disk failure, administrator or server automatically carry out fsck operation, which may cause more serious data loss or increase the difficulty of server data recovery. The mkfs operation is performed after the server data is lost, and if the operation is not completed, it is easy to cause part of the block group to be all zero. Or the administrator attempts to recover the data after the server data is lost, or the improper operation of the data recovery company may cause further damage to the data in the server and increase the difficulty of data recovery.

[correct method for server data recovery]

First of all, it is necessary to make a full mirror backup of all the data of the failed server, and data recovery must not be analyzed and restored in the original disk (this is the case for all storage media, including the server). Analyze the image file to determine the disk partition composition of the server, the remaining space allocation, what the file system type is, and whether the super block state of the root partition is normal. According to the super block status, check whether the description of the first block group is normal and whether the status of the node area is 0.

Since the description status of the first block group has been queried, and then the other block groups are analyzed in turn according to the description table of the first block group, the query rules. For example, in the sequential server data recovery, we find that the first 26 block groups of the user server are all 0, and the source data areas of the last part of the block group are all 0, but the description table, node, BITMAP and other information of the middle block group area are all normal. There is an obvious phenomenon of user data in the data area in front of and behind the block group.

Try to find the root directory of the server and use this as a clue to restore the root node area of the server, combined with the root directory records to generate a file system tree, (server data recovery has already seen part of the data) check whether the structure of the file system is normal, pay attention to whether the node of the file or folder is 0, trace the file node to find the node area is in the location of the file system. If a file or folder with node area 0 is found in the file system structure check, it is usually difficult to repair and export this part of the data.

[server data recovery recommendations]

If the data inside the server is very important, try to use the raid array of multiple hard drives as the storage environment, and avoid using a single hard disk to build the storage environment; the data in the server must be backed up regularly, and the backup package should not be stored in the same storage body as far as possible, and if the conditions really do not allow it, avoid storing it in a unified partition. After the failure of the server disk, the backup work should be done as soon as possible to avoid repeated attempts by non-professionals to repair; when choosing a data recovery company, try to choose a professional company to operate to avoid intentional or unintentional secondary damage.

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