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EMC storage crash raid offline data recovery method is what, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, hope you can gain something.

Overview of Riad data recovery failure

A storage of a certain company has mounted a raid5 disk array, and the storage suddenly crashed in normal use. After inspection by the administrator, it was found that two hard disks in the raid5 array were offline. One of the two hot spares in the array failed to activate, and the raid5 array was paralyzed so that the storage could not be used. A data recovery operation based on the raid5 disk array is required.

Raid5 Array data recovery Detection:

The hardware engineer first carries on the physical inspection to the two offline hard drives in the raid, the hard disk has no physical fault, no bad path. The upper layer of the storage consists of a lun for sun minicomputer and ZFS file system.

Raid5 array data recovery process

1. Backup data

All disks are fully mirrored according to the data recovery process, and engineers use data recovery tools to mirror all disks into files, and then convert the backup data from 520-byte sectors to 512-byte sectors to facilitate later data recovery operations.

2. Analyze the structure of RAID group.

According to the working mode of the disk array, we know that the LUN is based on the RAID group, so we need to analyze the information of the underlying RAID group first, and then reconstruct the original RAID group according to the analyzed information. The engineer analyzed all the disks and found that the Hot Spare of disk 8 replaced the bad disk of disk 5. However, another hot spare is not activated, so the data is not synchronized. Continue to analyze the other 10 hard drives, analyze the distribution of data in the hard drive, the size of RAID stripes, and the order of each disk.

3. Analyze the disconnect reel of RAID group.

According to the RAID information of the above analysis, a careful analysis of the data in each hard disk shows that the data of one hard disk on the same stripe is obviously different from that of other hard drives, so it is preliminarily judged that this hard disk may be the first to be offline. Engineers use a self-use RAID check program to check this stripe and find that the data obtained by removing the hard disk just analyzed is the best. So you can identify the hard drive that went offline first.

4. Analyze the LUN information in the RAID group and interpret the file system

Analyze the allocation and data blocks of lun through the reorganized raid, use the data recovery software to lun all the data, and then parse the file system operation to the exported lun. Normally, the data can be restored at this time. However, the parsing file system reported an error, and the engineer checked the file manually and found that some of the metafiles were corrupted, which led to the system not being able to parse automatically.

The above analysis makes it clear that some of the file system metafiles of the ZFS file system are damaged due to storage paralysis, so these damaged file system metafiles need to be repaired in order to parse the ZFS file system normally. Based on the analysis of the damaged metafiles, it is found that the storage of ZFS files is paralyzed while the IO operation is being carried out, resulting in some file system metafiles not updated and damaged. Manually repair these damaged metafiles to ensure that the ZFS file system can be parsed normally.

5. Export all data of raid array

Use the program to parse the repaired ZFS file system, parsing all file nodes and directory structures. Export, the data was recovered successfully.

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