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

IBM V7000 storage is a storage device located in the middle, and many enterprises choose this server as storage. Recently, North Asia data recovery Center received a case of V7000 server data recovery. The following will summarize the data recovery process and data recovery methods, hoping to help administrators in the operation and maintenance work of the server.

Server status description:

The server failure that requires data recovery is characterized by the loss of vdisk and the failure of the database in the operating system. The administrator rebuilds the MDisk, the original raid10 is rebuilt to raid6, and then to riad10 again. This series of operations lead to the loss of VDisk in the corresponding storage pool of the server, thus affecting the normal use of the Oracle database in the upper Solaris operating system. The customer needs to restore two sets of databases in the original server operating system.

The first step of data recovery: backup

All data recovery must not operate on the customer's original disk, so the first step in any data recovery operation must be backup. In this case, we link all VDisk involving Oracle database to the backup server in read-only mode, and use professional data backup tools to back up the mapped VDisk in read-only mode. Then sort all the member disks of the server and take out the IBM V7000 disk cabinet in normal mode as a full mirror in read-only mode. Restore all links and physical hard drives after the backup is complete.

MDisk and VDisk recovery methods

First of all, we need to judge the damage degree of the Mdisk reconstruction operation to the data, then analyze the distribution rules of the reconstructed raid6 data, and calculate that the double checks of RAID6 are written to the specific location of the hard disk. Because the double check of raid6 will destroy the data area, we combine the distribution rules of raid10 to restore the original Mdisk as much as possible.

After the above series of operations, we have restored the Mdisk of the server, and then analyze the underlying volume of the recovered Mdisk, take out the data MAP in reduced mode, and verify whether the data MAP is normal. According to the reduced mode algorithm combined with data MAP, restore VDisk as much as possible.

Database file recovery and database file repair

After completing the data recovery operation of VDisk, the Oracle database page feature scan is done with the undamaged VDisk, the corresponding database file feature set is generated, and the data distribution MAP of the database in all VDisk is analyzed to restore the database file. Here, we need to scan the database file with the help of our own software when checking the consistency of the database file. The scan result file is normal and structurally complete. Try to start the database instance and monitor the status. Everything is fine. Export the database. The data was recovered successfully.

Analysis of BM V7000 Storage MDisk Reconstruction data recovery

Because a MDisk in the IBM V7000 storage has been rebuilt, the upper VDisk and Oracle databases cannot be used properly. If the rebuilt type of MDisk is RAID6 (formerly RAID10), it will result in partial data corruption. In a worst-case analysis, the data of 2 disks (double parity of RAID6) will be corrupted (in fact, not completely). In terms of damaged VDisk, the data integrity will exceed 75%. The upper Oracle is composed of multiple VDisk, so the data integrity of the upper Oracle layer is more than 95%.

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