How to deal with the situation eva memory crash?

A fault description
the user is holding an HP EVA storage 4100, 23 hard disk capacity of 300G optical fiber, to map the upper one with windows on the server system, there are three disks began to see yellow light, this time is stored It can be used normally, after the user started to replace the hard disk contact operation and maintenance business, in the process of replacing the hard disk, hard disk appeared bright yellow light off, this time the collapse of a whole can not be used to store a user to four hard drives were tested under found four hard disk where the disk head and the occurrence of damage, only to recover data from a hard disk onto the remaining 19.
Second, the backup data
taking into account security and a reduction of the data, the data recovery needs to be done before doing backup of all source data, just in case other causes of data can not be recovered again. The read-only disk in a manner to mount a normal backup server, dd command as all disks into image files.
Third, failure analysis
1 analysis process
after the disk after detection, there are four physical hard disk fails, the disk is damaged, damage to the disk, the data can not be backed up on the hard disk, so that four hard disk completely damaged, can not used, only the remaining 19 to recover the hard disk, the hard disk because before 3 when they are offline, the normal use of memory can, after four hard disk offline stores collapsed, so down in the case of absence of a disk recovery, you can predict there will be some data missing.
2, the recovery process
(1) to parse the basic information analyzed by the header information, as shown below:

(2) RSS parsing group information, the group information in the RSS eva doing restored more important, as shown below:

(3) resolved lun information, after parsing lun analyzing data on the addressed bit map information, as follows:

(4) MAP parse parse the data and bitmap information, the information extracted through lun MAP bitmap information, the bitmap information through the MAP, the data blocks and combined into a logical parsing, as shown below:


IV Conclusion data recovery
User data is stored in the hard disk off-line due to excessive lead to storage problems can not normally access, offline hard drive has a hardware disc scratches, can not recover data off the hard drive. Based on the understanding underlying structure EVA4100 storage, and treated with a similar type of fault experienced. And the required data files are small users, so the whole recovery process fairly smoothly. The data recovered through user verification, so far, data recovery success.