RAID 5 is a redundant array, which consists of independent disk configurations. It uses disk striping with parity. In this array, data and parity are striped across the disks so not even a single disk is bottlenecked. This stripping allows users to recover the data in case of a disk failure.
Out of all the RAID configurations, RAID 5 is the most commonly used because of being evenly balanced. It has more storage than RAID 1 and RAID 10 configurations and its performance is equivalent to RAID 0. It has a minimum of 3 hard disk drives and no maximum limit. Raid 5 is considered to be the most secure configuration because the parity data is spread across all drives.
RAID 5 groups have a minimum of three hard disk drives (HDDs) and can have up to 16 HDDs. Because the parity data is spread across all drives, RAID 5 is considered to be one of the most secure RAID configurations. Striping provides better throughput and performance. Disk striping alone does not make an array error-tolerant; however, disk striping combined with parity provides redundancy and reliability.
Instead of mirroring, RAID 5 uses parity for data redundancy. When the data is written on a RAID 5 drive, the system calculates parity and writes it into the drive, whereas mirroring maintains multiple copies of data in every volume to use in case of any failure. RAID 5 can rebuild a failed drive by using the parity data which was not kept on a single drive.
Reasons for Raid Drive Failures
The main strength of RAID 5 is the fact that parity information is distributed among the drives so even if one (only one) of the drives fails, others keep working fine. Everything will continue to operate without any data loss.
Still, there is a possibility of damage while array rebuilding. Rebuilding is a time taking activity and often causes drive failures. Moreover, it requires reading data from all disks and increases the chance of the second drive failure, and can lead to failure of the entire array.
Another scenario of RAID 5 failure is when it tries to put the array back online with one failed drive. Although the description of RAID 5 says that it can operate with one failed disk, but actually most RAID 5 controllers have a “force online” function through which they push the array back online. But if the wrong drive is pushed back online, it can corrupt the entire array within no time.
So, to summarize, RAID 5 can fail due to the following primary reasons:
- Failure of two drives at once.
- Forcing RAID 5 array back online with a failed drive.
Other more common reasons include:
- Malfunctioned controller
- Missing RAID partition
- Incorrect RAID volume configuration
If you wonder why even one of the RAID drive would fail in the first place, remember that RAID is comprised of hard drives. The reasons for its failure could be the same as that are for any other hard drive.
- Sudden power surge
- Virus / Malware infection etc.
- Software/hardware malfunction
So if you rely on RAID 5 for storing data and the drive failure causes inaccessibility of data, you can suffer a huge data loss. But this situation can be avoided with the help of recovery techniques methods. Read continue to know how to recover data from raid 5 failure.
Methods – How to recover data from Raid 5?
In most cases of RAID 5 failure, all data is recoverable if actions are taken timely. Following are a few initial steps required to recover data:
Shut down the PC
First of all, shut down your PC. The reason behind this is that there might be a chance that while 2 of the RAID disks have failed already, the controller might still be working and keep writing on other drives causing them to fail too. So to avoid such a scenario, it’s better to shut down your PC until you figure out the issue.
Arrange the required resources
Arrange the necessary hardware and software required to perform RAID recovery without interruptions. Things that you will require include:
- An extra PC or external storage (preferably NAS) with enough space as the total size of original RAID disks.
- A UPS that can power your PC, the spare PC or NAS, a router and an HDD dock if required. No power interruptions should halt the recovery.
- An external HDD dock or another spare PC where your failed RAID disks will be attached to a bootable Windows OS for recovery.
- Trustworthy RAID 5 data recovery service provider.
- After you have all these resources, you have to:
- Disassemble all the drives from the RAID array, and one by one check their physical integrity by running your drive vendor’s diagnostic utilities. You are doing this only to identify failed drives, not recovering them at this stage.
- Note down the numbers/names and other parameters of the failed disks.
Once you have identified and noted the failed disks in the RAID, you can safely recover the data from the disks by taking help of a reliable RAID recovery service provider such as Stellar® Data Recovery services. Stellar – by way of leveraging its 25 years of experience and expertise in data recovery domain, highly skilled people, and specialized infrastructure and tools – ensure up to 100% recovery in diverse data loss scenarios. For instance, Stellar had recently recovered data from a Crashed Dell® Storage Server with RAID 5 Configuration. Earlier, the data recovery expert had also recovered 34TB data from a Barracuda® NAS.
Wrapping it up
We hope this article would help you to successfully recover data from raid 5. To avoid loss of data you should always maintain a reliable backup of the data.