Hello everybody!
Watch this video to find out how to recover data from a RAID array after a controller
failure.
You will see how to create a RAID 5EE system with the help of an Adaptec ASR-6805T controller,
what to do if one or several disks within the array failed, and how to restore the lost
information after a controller failure - and even if that controller is dead.
Losing important data is something that you can never predict.
Although RAID 5 is one of the most reliable solutions to store data among other disk array
types, it can’t guarantee 100% protection against data loss.
At any time, one or several disks may fail, and this is also true about the controller,
or other hardware.
How to create a RAID 5EE First of all, let’s explore the process
of creating a RAID system, the important aspects to be considered when building it, and the
settings required to make data recovery possible.
Our RAID will consist of six disks working with the controller, Adaptec ASR-6805T.
In order to access the controller’s BIOS after hardware initialization, you should
press the key shortcut Ctrl+A while the computer is booting.
In the menu, select Array Configuration Utility.
After that, you need to initialize the disks in order to tell the controller which of them
will be used in the array; open Initialize Drives.
Use the Space or Insert key to select every disk, and then press Enter.
As a result, you will see a notification warning you that information on all initialized disks
will be erased.
Hit Yes to confirm your decision.
After initialization, we can get down to business, so open Create Array.
Select the disks that your RAID will consist of, and press Enter.
Now it’s time to configure some properties.
Some of them are really important and it’s better to memorize them - you will need this
information later when you try to recover data from the disks.
Specify the array type, its name and size, block size, caching settings and so on.
That’s all, the array is built.
Now let’s find out how to replace a disk that failed.
Replacing a failed disk and backing up At this stage, we are going to simulate a
situation when a single hard disk fails.
RAID 5 is designed in such a way that it remains operable if one of the disks breaks down.
After a drive fails, the array becomes degraded, and while the computer is booting, you will
see a message like this.
Before taking any action, you should back up all important information, because virtually
anything may happen during the array rebuilding process: one more disk may fail, the process
may freeze, or there might be a hardware issue - but all of those nasty things can result
in a total loss of data.
A bit later, I’ll show you what to do, if the worst thing has already happened, but
at the moment, let’s rebuild the array.
Connect a new disk to the controller, turn on the computer, and open controller properties.
Your first step is to initialize the new disk.
Then add it to the array.
Open the menu to access the line Manage Arrays, press CTRL+S and open the management page.
Press the Space key to select the new disk and hit Yes to confirm your decision.
It should start the rebuilding process.
From now on, you can boot the server in normal mode and continue your work.
A complete RAID rebuild is quite a long process and it depends on a number of things - the
performance of your controller/disks, current controller load/disk load, etc.
It seems that the process will be much faster if you don’t choose to start using the array
as soon as the new disk has been added.
If possible, let the controller finish the rebuilding process and only then start using
the array the way you prefer.
But what should we do if several disks fail at once, the operating system won’t boot
after you added a new disk, or if the controller breaks down?
That’s when you need Hetman RAID Recovery to help you!
This tool lets you recover data from crashed RAID systems or disks that were used in such
array, it reads all the information about the controller, the motherboard, or the software
used to create a disk array.
Our product can rebuild the crashed RAID and it lets you copy all important information
from there.
How to recover data from a RAID array with a dead controller
When the controller fails, you won’t be able to access the information on the disks.
When connected directly to the computer, the operating system will ask you to format the
disks for further use.
In this case, you will either need a controller of the same model (which doesn’t guarantee
the success of this operation, though) or a software tool capable of uniting these disks
into a RAID system, displaying and restoring your data.
Connect the hard disks to a Windows computer.
The operating system will display them as RAW and suggest to either initialize or format
them.
No matter what, don’t choose anything - this way or another, you are taking the risk to
lose all the data for good.
Instead, download, install and run Hetman RAID Recovery.
In fact, a lot of service information is written to the disks included into a RAID system:
what disks make up the array, in what order they are connected to the controller, the
RAID type, block size and the procedure of writing blocks, number of disk groups, and
the data on the array size.
Having collected all the available information from the system and connected disks, the utility
displays the automatically built arrays immediately, as soon as the program starts.
In most cases, the program manages to restore RAID on the fly and suggests you to analyze
the identified partitions and save any available data.
Open the Drive Manager tab, and find the line RAID Arrays to select your storage system
from the list.
Right-click on it and choose Open.
Try Fast scan first: if the disk structure is not damaged, this scan type will suffice.
If the fast scan can’t find the missing data, then go for Full analysis.
When it’s over, the program will display the results in the right side of the window.
You can see that the program has built the RAID without effort and it can now display
all the information still available on the disks.
In this case, you don’t have to buy a controller of the same model - and as we know, even when
you have it, there’s no guarantee you can build the RAID again without losing its information.
SATA expansion cards If you don’t have enough SATA ports to connect
all the disks, there’s an easy solution - buy an expansion card.
They are numerous and easy to find, for example, on AliExpress.
To have all the disks connected to the computer, we used an expansion card model Marvell mv91xx
(PCE6SAT-M01) with six ports.
Initially, the computer was only able to detect 4 disks, and to make it “see” all the
disks connected to the expansion card, we had to install corresponding drivers.
Expansion cards may have 2, 4, 6 or 8 ports.
Using a card like that, you can connect up to 8 disks, and if we also use the remaining
vacant ports on the motherboard, it all comes up to a huge array of over 10 drives.
Recovering data in a case of dead controller and one hard disk
Now let’s simulate a situation, when both the controller and one of the hard disks failed.
If one of the disks fails in this RAID type, the array remains completely operable, but
when things get from bad to worse and the controller is out of order, there is nothing
you can do without specialized software tools.
Let’s see how our program copes with this problem.
Connect the remaining five disks directly to the motherboard of our computer, turn it
on, and run the program.
Hetman RAID Recovery detected the RAID type automatically.
Right-click on it and open the array.
At first, select Fast Scan.
The program can recognize all the files that have been written to the array.
To have them restored, select the necessary files and click Recovery, specify where to
save the information, and click Recovery again.
When the process is over, you will find the recovered files in the folder you have chosen
for saving them.
Recovering data in a case of dead controller and two hard disks
Now let’s simulate a situation, when both the controller and two (!) of the hard disks
failed.
In such case, this RAID type gets out of order, even though the controller is OK: in fact,
the information is lost.
Replacing the failed hard disks is not going to change anything.
All right, we have four disks connected to the motherboard directly.
In your case, if you don’t know for sure which disk failed, it’s better to connect
all the disks that your RAID consisted of.
In my case, I’m only trying to simulate a situation with two hard disks failing, so
I just disconnect them.
Let’s start the program, and you can see that even in this case, Hetman RAID Recovery
managed to detect the RAID type automatically.
If your RAID is not on the list, you can still use RAID Constructor.
In our case, the array type was detected automatically in the Constructor.
To rebuild the array in manual mode, you will need all the information you have on this
RAID.
Previously in this video, I emphasized the importance of memorizing its properties when
creating the RAID system.
If the program has detected the array type automatically, view the information in the
next window to make sure that all the properties were detected correctly.
This is the factor that determines how much data can be recovered.
If one of the properties is incorrect, change it; if everything is correct, click Add and
scan the disk array.
You can see that the program has found the data, and some of the information is damaged.
In this case, you can try running Full analysis, and it may help you find even more data.
Now select the files you want to restore, click Recovery, specify the directory where
you’d like to save the data, and click Recovery again.
When the process is over, all the information will be placed into the folder you have chosen
for saving it.
Conclusion In the end, we managed to recover a certain
share of important information from a RAID system with a dead controller.
It is a good result, because if two disks within such RAID fail, it typically renders
the whole array inoperable and all the data might be gone.
That is all for now!
Hopefully, this video was useful.
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Thank you for watching.
Good luck.