What happens when RAID fails?

What is RAID? Why and when do you need one? What is the most well-known RAID recovery software? Is it possible to recover data from RAID? What are the reasons and consequences of RAID fail? Interested? Keep reading we know the answers.

RAID stands for Redundant Array of Independent (or Inexpensive) Disks. This term describes the system which allows combining several independent disks into one large size storage. Why? Well, today people handle a lot of huge data and sometimes it just seems too crowded for all of them in one place, no matter how large memory we are talking about. So, this is a job for RAID.

All those small hard disks gathered in the array represents array members. There are few ways to combine array, so called RAID levels (RAID 0,1, 0+1, 1E, 5, 5E, 5 with delayed parity, 6,).

Also, each of those levels has special characteristics of:

  • Fault tolerance – capability to survive one or several disk failures
  • Performance – it presents the change in the read and write speed of the whole array in comparison to a single disk
  • The capacity of the array – which is determined by the number of users data which could be written to the array. The capacity of the array depends on the RAID level.

All RAID types are based on three main methods for data storage or combination of these techniques:

  • Striping – the way of splitting the flow of data into blocks of a certain size and writing blocks across the RAID. This way of storage affects the performance
  • Mirroring – a special technique of data storage which allows identical copies of data to be stored on the array member disks simultaneously. This type of storage affects on the fault tolerance and performance.
  • Parity – this technique of data storage combines striping (splitting data into the blocks) and checksum methods.

What RAID implementation to choose, hardware or software?

We bring you some facts you should know about both solutions.

Hardware RAID has two solutions, inexpensive one – RAID chip, which can be built into the motherboard, and more expensive solution with a complex standalone RAID controller. The advance of this expensive solution is equipment which could include its own CPU, battery-backed up cache memory and hot – swapping support.

A few advantages that hardware RAID has over the software RAID maybe will help you to decide which one you really need. For example, it doesn’t use CPU of the host computer and user can create boot partitions. Communication with the device is directly so it can handle errors better, which, you have to admit, is great and it supports hot swapping.

What about software implementation?

If you have home edition of Windows you will be able to install only RAID 0, while, for example, RAID 1 and 5 are created for Windows server edition. Unlike the hardware RAID, the software implementation in most cases doesn’t implement the hot swapping. Also, it uses CPU of the host computer. It is useful to know that some limitations exist when it comes to system boot which is possible only in RAID software.

Why and when do you need RAID?

RAID is still mostly used in companies with large servers which need access to their critical data 24/7. One of the advantages surely is the simple usage of data in the array.

Although, RAID is also used among private users who want to avoid monthly fees this way and who has some kind of mistrust when it comes to cloud storage services. The most common users are multimedia editors and computer-aided design (CAD) users because they appreciate RAID advantages like high fault tolerance and fast transfer rates. We shouldn’t forget to mention computer gamers here, who also appreciate RAID’s setups.

It is important to know that RAID is not a substitute for regularly backup. True, it can protect against disk failure in some way, but it is not a protection against administrator errors or the one caused by bugs in programming.

RAID fails too – reasons and consequences

When you are faced with hard drive failure it is very important to stay calm. You shouldn’t take any reckless reaction. Although RAID is considered to be a safe system, it can collapse too, even more, that is not so unusual situation.

Users often get panic because they don’t expect RAID to fail. According to the experience of one of the companies that solve this kind of situations, the manufacturer’s support advise you to delete the RAID configuration and try to recreate it. Well, do not do that in any case. It can cause you a permanent damage.

What you should o do when you suspect on RAID failure:

  • If you can hear any unusual mechanical noise from the drive, turn it off promptly – this is one of the situations when we recommend you to call a specialist.
  • Do not run volume repair or defragmenter utilities on suspected bad drives
  • Do not try to replace a failed drive with the one from another RAID system
  • Mark the drives on their position in a RAID array

Three general RAID failure reasons

  • One of the RAID member disks failed
  • Several RAID member disks failed
  • Other failures that are not related to member disks. It can be controller failure or operator error.

Is it possible to recover data when RAID fails?

When it comes to RAID failure there are some rules you should follow. For start, when you realized you are facing the RAID failure, you need RAID recovery. The first step is to write down everything you know about original array configuration.

In a hardware configuration, it means you have to mark all the member disks along with controller ports and cables.

On the other hand, you have logical RAID configuration which refers to RAID type, disk order, a number of member disks, block size, start offset for the data on the member disks (if this information is available).

If you want to return to the original configuration, you have to collect all the above-mentioned information.

How to prepare member disk for recovery and what you will need?

  • Disconnect disk from a controller
  • Don’t try to rebuild an array using the same or another controller if you don’t know correct the RAID parameters.
  • Always create the disk image files from separate disks instead from entire array. The thing is that some parts are inaccessible unless you disassemble the array.

After you detected all parameters you have two possibilities to move on with RAID recovery process. In case you need all RAID’s content write somewhere a copy of the RAID and if you need just some files, you should use regular data recovery program.

The most common problems when it comes to RAID recovery are the capacity of data and sizes of the array. It is important to consider a configuration which is able to fulfill all resources needed in terms of speed and capacity. Sometimes you will need free disk space same size as files you want to recover, and sometimes situation could be more serious and demanded a two or three times more disk space to store simultaneously original disk images and recovered files.

5 most well-known RAID recovery softwar

  1. ReclaiMe Free RAID Recovery ( http://www.freeraidrecovery.com/)This is very simple to use software which doesn’t require special technical skills. It works with most common RAID types (RAID 0, RAID 5 and RAID 10). ReclaiMe RAID recovery doesn’t work with the single hard drive and there is no way to recover file by file, it can only handle array as one whole. Support Windows.
  2. Diskinternals (http://www.diskinternals.com/raid-recovery/)DiskInternals is a software which allows switching between automatic and manual modes. Also, it has the possibility to detects the type of the disk array automatically. Supports Windows.
  3. Runtime (https://www.runtime.org/raid-recovery-windows.htm)It provides recovery for NTFS-formatted Windows RAIDs and includes hardware RAIDs and Windows software RAIDs. Runtime is easy to use software, fully automated and runs from the Runtime Live CD https://www.runtime.org/data-recovery-live-cd.htm and WinPE boot CD-ROM ( https://www.runtime.org/peb.htm). Supports Windows.
  4. ZAR – Zero Assumption Recovery (http://www.z-a-recovery.com/)Powerfull software that works with RAID 0 and RAID 5. It runs only on Windows and Linux, doesn’t cover Mac.
  5. R-Studio Data Recovery Software (http://www.r-studio.com/)This is a collection of software which uses advanced techniques in data recovery. It works with RAID 0, RAID 5, RAID 4, RAID 6. Runs on Windows, Linux, and Mac.

What can you do to recover data from the broken hard drive?

Hard-disk drive is the main storage device of the computer which contains a few moving parts and if, for some reason, any of them goes down, the whole drive could suffer the damage. It’s the most fragile part of the whole computer system.

As we are talking here about our storage for documents, pictures, videos and many other important files, it’s not surprise that people panic when something goes wrong with it. Can you recover data ones the hard drive is dead and you haven’t made a backup? Or is it too late?

It is obviously you have a crisis situation to deal with, and it is not the time to sorrow now. Yes, you should have made that backup, but you haven’t and now you can only try to repair the damage. It is important to react really fast and advisedly.

How can we recognize that the problem is on the hard drive?

There are many signs which could warn you that your hard drive is reaching its end and you shouldn’t neglect them. Truth, all those signs could be warning for a bunch of other problems, but the point is in drawing attention.
In case you haven’t already made a backup, you should make one as soon as you notice one of this problems:

  • strange sounds from your hard drive
  • folders and files disappearing
  • long time needed to access folders and files
  • corrupted data – fail to open despite the fact they were correctly saved
  • scrambled file and folder names
  • Frequent and cryptic error messages during activities like moving files
  • Frequent crashes while booting up Windows

Even those signs may warn of some other problems, backup is always a good idea. Although, you shouldn’t rely on those signs to predict hard drive crash. Often hard drives fail without warning, so in one minute you work normally on your computer and in next you can face “blue screen of death”.

What are the main reasons for the hard drives crash?

As we earlier said, there are many reasons that can cause hard drives damage but all can be divided into two main groups: logical and mechanical (hard drive) failure.

data recovery questions

Logical damage includes:

  • track servo information error – it means that servo information of a certain physical track is damaged and the track can’t be accessed
  • system information area error – it happens when hard drive system information area can’t read data in some of the modules
  • sector logical error – warns that some sectors will become invalid and the main reason could be bad block mark error, verification error, address information error etc.

Mechanical (hard drive) failure:

  • head component damage – when damage has been done on one part of the magnetic head component
  • control circuit damage – it refers to some broken parts of the circuit line in the hard drive electronic circuit board
  • comprehensive damage – some minor changes like high temperature during using can cause many problems on the hard drive
  • physical bad track – physical damage on hard drive surface which could be caused by magnetic head friction or some other reasons.

Can we fix it by ourselves?

There are few tests you can run to find out more about broken hard drive. First, if our computer is running Windows, you should reboot the computer and go to BIOS by pressing the Delete key during the boot-up sequence. If the drive doesn’t show up it could be a problem with connections on relation drive – motherboard. But if the drive does show up, you should do more tests. Of course, you will need another functional computer for that action.

Next step is to find out manufacturer and model of our hard drive, so you could find the compatible diagnostic software and download it. Then you have to boot the damaged computer from the diagnostic disk and run it. This process should indicate where the problem is.

Also, you can create a bootable virus scan disk in order to scan the dead drive for viruses that may cause the problem. Until this moment you should already have some rough diagnosis. But what if none of these worked? You should try to connect the drive to another computer and see if the problem is really in the hard drive.

When is time to hire the professionals?

Here is one more test you could take. Open the computer case and listen when booting up, if it is silent you can conclude the platters aren’t “spinning up”, which indicates a mechanical problem.

When you are faced with the mechanical problem on the hard drive, you can try to fix it on your own but that means finding replacement parts from the exact model of the drive and sometimes that is not simple as it seems. There are some parts you might be able to replace on your own like a dead circuit board, but some parts like spindle motors or read/write actuators could be a problem and it is maybe better to leave them to professionals.   

You might have heard of some extreme method for hard drive recovery you can find on the Internet like sharp physical shock, freezing the drive, which should be a last resort when you have nothing to lose. Instead of that, we advise you to contact professionals.

What can you expect after you recover the data?

The hard drive is very easy to damage part of the computer, so you have to be extremely careful with solving a problem like this one by yourself. You have to be aware of the fact that maybe it won’t be possible to recover all data. Some of them could be lost forever, and some could be damaged. If you use some of the data recovery programs you have to know that, even if you recover data, they won’t be in the same condition they were before recovering. Recovered data will be organized by type, and the name of the files will be changed. So, the final result, in the best way, would look something like this: IMG2573.jpeg. It is obvious you will have to rename all recovered files, and that is a huge work to do.

In the end, you will probably agree on this – backup is very important part of our jobs. Do not forget to take one and spare yourself a big trouble.