Shulou(Shulou.com)06/02 Report--

As the saying goes, normal servers are in production, but abnormal servers have their own failures. As a server data recovery worker who has been engaged in server data recovery for more than ten years, most of the server data recovery cases encountered in recent years are similar, and there are fewer and fewer failures. I think on the one hand, I have been engaged in server data recovery work for more and more time, and general failures have been experienced, on the other hand, it is the result of server manufacturers' continuous optimization of the security performance of their products. However, although the failure that led to the loss of server data is relatively simple, the number of cases of server data recovery has not been significantly reduced. Today, through a recently handled case of server data loss, we will introduce the data recovery process of server hard disk disconnection.

First of all, the basic situation of the failed server is introduced. The server with data loss is a group of raid6 disk arrays. The array contains 8 hard disks, and the capacity of a single hard disk is 500g. The server is a web server, which is mainly used to run the database, and another part of the space is used to store ordinary office files. Due to the administrator's neglect of management or the fluke mentality, the hard disk of the server has not been replaced even though there are already two hard drives offline in this array, and soon another hard disk in the array is offline, and this last offline hard disk has become the direct cause of the server crash.

Before we received the customer's server, a data recovery company in Beijing had already carried out data recovery operations on the server and recovered most of the data, but the data was seriously damaged and could not be used. Office files were also lost for nearly 40 days, so the data recovery company had to recommend us, and customers came to our company with the server to make a second data recovery attempt.

After a brief understanding of the customer's server failure, our server data recovery engineer first mirrors all the hard drives to the data recovery secure storage pool, although it is not sure whether the last data recovery company did the same thing. However, in order to ensure the originality of the data, we still have to mirror the customer's original server. On the one hand, we are responsible for our data recovery company. On the other hand, it is also responsible for customer data.

Next, the server data recovery engineer analyzed the image files of the recoverable server and found that the first two hard drives in the array were offline very early, and no new data was written for at least two months. so the key point of data recovery falls on this last offline hard disk. The client's server array uses double parity, but because two hard drives are offline for a long time, ordinary XOR operations can no longer recover data from the server, so we can only use the second check method generated based on Reed-Solomon algorithm to recover data. This data recovery method is still one of the core algorithms of our company. There are no other similar algorithms and hardware and software products on the market, so this is why the last data recovery company did not successfully recover the data.

Since it is the core algorithm, I will not describe in detail our process of analyzing and recovering the data. The server data recovery engineers wrote a general Mini Program to reorganize and extract the corrupted data, and then generate a complete mirror. There is no problem in verifying the recovered data in the secure storage pool, and then contact the customer for final verification of the data. After the final verification by the customer, all the data in the server is restored, the database can be used normally, and the server data recovery is 100% successful.

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