Hello everybody!
Watch this video to find out how to recover data from hardware RAID 0, 1 or 5 which is
built on a Linux operating system - in case one or several hard disks break down.
A Linux-based hardware RAID is hardly a good example of a reliable storage system - if
one of the disks within the array gets disconnected, the whole RAID can’t be mounted, and all
the information becomes inaccessible in a second.
This is when you need a utility capable of building the array with the remaining disks
and displaying the data which is still there, and restoring this information.
Hetman RAID Recovery lets you recover data from non-operational RAID systems or from
disks within such systems.
It can read all the information about the controller, the motherboard, or the software
used to create the disk array.
With all of its functionality, it rebuilds the crashed RAID and lets you copy all important
information from there.
How to recover data from RAID At the moment, there is no version of Hetman
RAID Recovery for Linux, but running this utility on Linux is still possible.
Watch one of our videos to learn how, and you can find the link in the description as
always.
HOW TO START IT ON LINUX To recover information from a damaged Linux-based
RAID, connect the hard disks to a Windows computer.
If you don’t have access to such a computer, you can install a Windows virtual machine
or install this operating system as the secondary one along with Linux being your primary system.
How to recover data from RAID 1 For the first test, we have prepared a hardware
RAID 1 consisting of two hard disks and based on Linux.
RAID 1 includes two or more hard disks which are exact copies of each other.
Although it is very reliable, we couldn’t mount the array in Linux when one of the disks
failed.
It is still available in the disk utility, but there is no button to mount it, and the
automatic mount feature can’t be enabled too.
Hetman RAID Recovery managed to identify all properties at once, built and displayed the
disk array automatically.
In the Drive Manager, right-click on the array, open it, select “Fast scan” and click
“Next.”
When the scan is over, the program will display the results in the right side of the window.
It finds all data which is still on the disk like a charm, and the contents can be previewed.
Now all you have to do is to select the files to be restored, click “Recovery,” choose
the directory where to save the files, click “Next” and “Recovery” again.
When the process is over, you will find the recovered files in the folder you have chosen.
A hardware Linux-based RAID 1 is designed in such a way that it writes service information
on this array type to all of its disks (this information includes the number of disks,
their serial numbers, and where each disk begins).
That is why if one of the disks is missing, the program reads this data from other disks
and adds the data on the missing disk when building a damaged RAID.
In some cases, this information can be damaged, and while building the array the utility can’t
understand where the data on a certain disk is located, and what kind of offset is used
for a specific disk.
If that’s the case, the utility won’t find any data after the scan.
In order to find the information which is still on the disk, you’ll have to use the
RAID Constructor.
In addition to all the properties, you have to specify the offset by which you can locate
the beginning of the disk.
Every file system has specific signatures which help us to identify its beginning.
When you specify this offset, you’ll be able to rebuild the damaged RAID and extract
data from there.
To find the offset, use the HEX editor: right-click on the disk and open HEX, or press the key
shortcut Ctrl+H. In Linux, you can find the beginning of the disk by the field with the
name like /media/lin/ - where lin stands for the user account name.
As we know, information about the beginning of the disk in this file system is written
to the second sector from the beginning, so we need to go two sectors up.
After that, use a calculator to convert the HEX value into the decimal system.
In the calculator, select the programmer mode, select HEX and type this value (8200000).
After that, you get the value in the decimal system (136 314 880).
When you hover the cursor over the beginning of the sector, a window with some information
appears.
Now that we know the offset, specify it in the RAID Constructor, add the disk, scan it,
and have your data back.
How to recover data from a hardware RAID 5 Now let’s see how we can deal with RAID
5.
In one of the previous videos, I’ve already shown you how to create a hardware RAID 5
on Linux, so follow the link in the description and watch the tutorial to help you build any
kind of disk array that’s possible in your case.
Meanwhile, let’s find out how to recover data from this kind of storage system.
HOW TO CREATE RAID 5 ON LINUX RAID 5 is an array with redundancy, block-level
striping and distributed parity (which means that parity information is distributed among
the drives instead of having a separated drive allocated for this purpose).
It is designed to remain operable even if one of the disks fails, but in real life,
the situation is very different: with one disk down, the hardware RAID can’t be mounted,
and the data can’t be extracted.
In order to restore the information, you need to connect a new disk or use additional software.
For the test, we have created a hardware RAID 5 consisting of 5 drives, one of which was
damaged.
Connect the remaining disks to a Windows computer, or add them to a virtual machine.
Without difficulty, Hetman RAID Recovery had identified the array type and its properties.
As you can see, one of the disks is empty.
(Right-click on the array - Properties - the RAID tab).
Right-click on the RAID and choose “Open.”
Analyze the array with the help of “Fast scan.”
You can see that the program finds all data remaining on the disks without difficulty.
Select the necessary files and click “Recovery,” choose where to save them, and hit “Recovery”
again.
In the end, you’ll find all the information in the folder you have specified for saving.
Even though several disks within the array were down, the program managed to identify
the RAID type, its file system, and other properties.
Two disks are empty (right-click on the array - Properties - the RAID tab), so let’s scan
them and see what can be found.
Right-click on the array, open it, select “Fast scan” and click “Next.”
As a result, the fast scan couldn’t find any healthy data - all the data it has identified
is damaged.
Let’s try a “Full analysis” then.
With “Full analysis,” the program can find the data still remaining on the disk,
but some of the information is damaged.
If two or more drives within this RAID type break down, it becomes completely inoperable,
and it’s rather difficult to recover any data from there, so this result is actually
quite good
when we manage to recover a part of the remaining information.
Select them and recover.
How to recover data from a hardware RAID 0 For the last test, we have built a RAID 0
consisting of five hard disks.
If one disk in this array breaks down, the whole storage system becomes inoperable and
all the information is actually lost.
We can’t mount it in Linux either - the disks won’t open.
Let’s see if we can extract at least a bit of the information with the help of Hetman
RAID Recovery.
A RAID 0 is a high-performance striped disk array without parity information, redundancy,
or fault tolerance.
If even one disk fails, the whole array becomes inoperable.
Technically, it’s not even a true RAID system because it doesn’t have any redundancy.
The program has identified the array type and properties, and one disk is empty (right-click
on the array - Properties - the RAID tab).
In this case the fast scan hasn’t found anything, so we need to use a deeper scan.
After the Full scan, the utility can find the data, but some files are damaged.
Hetman RAID Recovery managed to detect a part of the remaining information.
Select the files you want to restore and click “Recovery,” specify where to save them,
“Next,” click “Recovery” again, and when everything is ready, hit “Finish.”
All the files will be placed into the folder you have specified.
Summing up, we can say that all the data still remaining on the disk can be recovered: in
some cases, all you need is to specify the offset to help the utility find the beginning
of the disk, and some other important properties.
In the end, the program will be able to determine where to look for the missing data, display
the files, and give you the opportunity to recover them.
In some cases, data can only be recovered partially, but still, it’s better than nothing,
right?
That is all for now!
Hopefully, this video was useful.
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Thank you for watching.
Good luck.