Configure RAID-5 Following a Disk Failure
In this article, you will read about RAID-5 array rebuilding and causes of RAID failures. With the help of this article, you will also get know what things you should do to prevent data loss and how to recover data from failure RAID-5.
The Raid-5 array is one of the most common means of providing Mass storage along with a fault tolerant vault. That is to say, if ever one of your hard disk suffers a complete breakdown, even so you won't lose your data. It will be tolerated. Only, the RAID-5 will be reduced to RAID-0. At times 'Enhanced data availability' is also used to define 'fault tolerant'. Users often end up thinking it is synonymous with 'Data loss prevention'. However, it is not so.
Here are a few things you must know about RAID array-
• At least three or more hard disk drive elements make up an array.
• While RAID-5 is fault tolerant, it is limited to only 'One disk failure' (2 in case of RAID-6).
• Make sure all your hard disk drivers and controllers are working properly else your RAID-5 will inevitably fail.
That being said, it becomes easy to establish that failure of one or more members of hard disk or of any other small part can cause RAID-5 failure. You can detect that one of the hard disks has crashed, if
• LED corresponding to the damaged disk turns red, in case of NAS
• 'Disk has failed' message pops up constantly by the RAID-5 controlling software
• The controller is working properly but still the array isn't accessible
Logical RAID Configuration
RAID recovery actually means the recovery of Logical RAID configuration. This contains the following parameters:
• Type of RAID and the number of hard disk drives
• Order of disk and the block size, if applicable
• Start offset for the data on member disks
Usually the RAID controller BIOS or RAID monitoring and configuration software contain the logical RAID configuration. Once all these parameters are accounted for, RAID recover is pretty much done for you, since all this information helps rebuild the missing RAID configuration parameters.
In case of any of the above cause or indication, go through the steps below to rebuild RAID-5.
• Verify the current state of your array disks and secure them. Make sure to label the disks, ports and cables.
• First, disconnect the array disks. Now, connect these array disks to the controller which can still work with separate disks. Be it a RAID-controller or a non-RAID Controller.
• Now, you need to recover RAID parameters. You can use a third party tool for this.
• If it's a hardware RAID, write the array to the disk corresponding to the third party tool.
• Try mounting the disk in whichever operating system it was used. In case the disk you have isn't large enough, use a temporary array to write data. Don't ever write the data of array to the members if the original disks.
• In case of a Software RAID, use a third party software recovery tool. For this upload the image of array file to the data recovery tool.
• Load the parameters of the array to the software recovery tool.
• Save and check the large files to make sure that the data is reconstructed properly.
• Now, you can rebuild RAID and copy your original data.
DO'S AND DON'TS
• Do label the storage configuration array during the initial setup, especially disk drives.
• Do tag the physical disk drive unit to maintain the sequence of array members.
• To avoid a drive failure, make sure to test the subsystem's ability. Back up your data and replace one of the drives while the subsystem is still running with a blank hard drive.
• If more than two hard disks have broken down, there is no way to bring back your stored data except for using high-level data recovery techniques (microcom).
• Do not try to rebuild the RAID, until all the hard disks are accounted for and are fully functional independently.
• Rebuilding RAID-5 is not necessarily for data recovery. (It is just to increase data availability).
• Do not switch the positions of the hard disk drives until and unless you are absolutely sure that the controller will be able to recognize the changes.
• Do not use files like CHKDSK, or so do so with extreme caution.
STELLAR PHOENIX WINDOWS DATA RECOVERY
While you can find many third party software for RAID-5 rebuild, we highly recommend the 'Stellar Phoenix RAID Data Recovery'. This third party software helps with data recovery from hard disk as well as external drives. With a very powerful search engine and an efficient algorithm it makes the recovery of lost files that much easier. It can scan more than 2 TB of data and works on Windows Vistas and all the versions above. It also supports NTFS, FAT and ExFAT file systems. The Stellar Phoenix Windows Data Recovery software can easily bring back your deleted files form corrupted hard disks, pen drives and memory card. The extremely user friendly interface provides a convenient platform for novices as well as professionals.