RAID Failures & Overcome the 5 Most Common Causes
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What will it take to get RAID failures out of your life for good? Start right now by learning a bit more about what’s behind these eternally unwelcome events.
It may seem uncanning to figure out how to avoid a server failure. Sure, you can opt to go with the RAID recovery services of our choice if your circumstances does not allow you to troubleshoot.
But in this guide we’re going to pick the basics up for anyone of you who wish to avoid this issue in a future troubleshooting.
What is RAID?
RAID, or Redundant Array of Inexpensive (or Independent) Disks, links two or more hard drives to form one large capacity storage device. RAID enables users to store the same data on multiple hard disks, offering improved performance and reliability. It also reduces the risk of losing data in the event that one or several of the disks fail (fault-tolerance) as well as expand data storage capacity.
Depending on the RAID level, an array uses Striping, Mirroring, and Parity storage techniques or a combination of these techniques.
RAID Levels
- RAID 0 - uses Disk Striping technique
- RAID 1 - uses Disk Mirroring technique
- RAID 5 - uses Striping with parity technique
- RAID 6 - uses Striping with double parity technique
- RAID 10 - Striping and Mirroring techniques
RAID Levels and Their Specific Weaknesses
RAID 0 - Not Best For Mission Critical Systems
RAID 0 is also known as disk mirroring. The RAID 0 has a configuration of at least two drives that duplicate data storage. You can optimize your storage capacity but there no overhead.
It is recommended when you want to read/write stored data at a high speed. Graphic designers and video editors use RAID 0 for their workstation.
However, despite its good performance in both read and write operations, it isn’t recommended for mission-critical systems because RAID 0 is fault-tolerant. When one drive fails, all the data stored in the RAID 0 array is lost.
RAID 1 - No Allowance For Failed Drive Swap
The RAID 1 offers users more diverse use over the RAID 0. In RAID 1, you are free to store data in two locations. The first is the live dataset while the second is a mirror drive. It also has great read/write speed compared to RAID 0 since it doesn’t rely on a single drive.
This means you can recover your data from the mirror drive in case your live dataset fails.
However, it’s pitfall is found in its storage capacity. Since all the data in RAID 1 gets written twice, it demands high storage capacity to continue operation.
RAID 5 - Failures Have a Direct Effect on Throughput
The most secure RAID level is RAID 5. It can handle a single drive failure without losing data. This is possible because of parity data. Parity data is spread across all drives rather than written on a fixed drive like data does with RAID 0 and RAID 1.
It usually requires at least 3 drives but can also work with up to 16 drives in one data configuration.
It can read data faster but is slow when writing data. To improve RAID 5 write performance, you can use extra cache memory on hardware controllers in achieving RAID 5 in software.
The downside is how complex the RAID 5 technology is. Its drive failure has a tendency to affect your output. It takes over a day or more to restore data when one of the disks in an array using 4TB disks fails. And when other disks go bad during recovery, your data is permanently deleted.
RAID 6 - Failure have a Direct Effect on Throughput
RAID 6 is similar to RAID 5 except its ability to write the parity data in two drives instead of one. It means RAID 6 requires at least 4 drives to work efficiently and can withstand 2 drives dying at the same time. Unlike RAID 5, it can also keep your data in the event of a second failure.
It is more expensive, too. In RAID 6, you’re using 4 drives as opposed to the usual 2 or 3 in other RAID configurations.
Very Complex Techonology Means Longer Repair Times
If you noticed, the more complex the technology is, the longer it takes to repair the drive damage. All RAID levels (except RAID 0) gives users protection against a single drive failure. Since the RAID 6 is one of the more complex ones, rebuilding an array or raid rebuild of one drive failure can take quite some time in contrast to RAID 1 and 5.
So even though the RAID 6 is great at storing and securing your data. You might have to be patient when a drive failure occurs. But with the RAID 6, you rest assured your data won’t be lost permanently when things go wrong.
Additional Parity Slows It Down
Due to the additional parity data in RAID 6, writing data transactions is slower. Users report the write performance of RAID 6 is over 20% lower than the other RAID configurations.
RAID 10 - Half of the Capacity Goes to Mirroring
RAID 10 is known as the combination of both RAID 0 and RAID 1. That is why it is also called a Hybrid RAID configuration. It gives users excellent security by mirroring data on secondary drives and uses striping across each set of drives for faster data transfer.
It can take just half an hour to transfer big terabytes of data and information. It takes just as long to rebuild it, too, when you encounter data failure.
With that said, half of its storage capacity goes to mirroring so the drive cost is more expensive than both RAID 5 and RAID 6.
RAID Techniques
- Striping
Splits data flow into blocks written across the RAID. This technique is aimed at improving performance. - Mirroring
Iidentical copies of data are read and written on pairs of drives simultaneously. This technique is for fault-tolerance and to enhance performance. - Parity
Uses striping and parity computations — calculates the data in the first two drives and storing the resulting data on the third drive. This technique provides fault-tolerance as well as improves speed. If any of the disks fail, data can be recreated from the remaining data and the Parity data.
Consult Data Recovery Experts When:
To a computer or network, a group of hard drives in a RAID configuration appears to be a single device, known as a logical unit number, or LUN. LUNs employ various hardware or software techniques, such as:
2. A Rebuild Didn’t Go as Planned
When you replace a RAID drive and rebuild the data that it formerly housed, errors could have disastrous effects. Interruptions in the process have the potential to corrupt existing data and make it impossible to access certain files or the entire RAID. If you experience a future failure or file loss, it’s unlikely that you’ll be able to recover.
3. More Than One Disk Failed
RAID disk failures don’t always come alone. You might lose multiple storage devices in a single cataclysmic event due to power problems or hardware age. Such events can have various outcomes depending on what kind of RAID you were running.
In some multi-disk failure situations, it’s possible to continue operating in a degraded, or compromised, mode. It’s worth noting that doing this increases your odds of suffering another failure in the future, and there’s no guaranteeing that the next one won’t be even worse.
4. The Partitions Mysteriously Went Missing
When used correctly, partitioning can help minimize speed loss on heavily used RAIDS or create functional redundancy arrangements on disks. When RAID features like striping fail, however, partitions may become so corrupted that the system doesn’t even recognize them. Although they’re not truly missing in the physical sense, they’re as good as gone to their users.
5. The Server Died
The networked machine that hosts your RAID suddenly quit working. Unfortunately, it’s not always as simple as just restarting the system. In some cases, a failed server could have taken other things down with it, so you need a reliable, comprehensive recovery strategy.
Identifying a Dependable Solution
What do these common failures share? As unique as they are, all RAID failures require expert troubleshooting assistance.
Trying to repair common RAID issues by yourself only increases the likelihood that they might mutate into more dangerous faults. Always play it safe by working with someone who knows what they’re doing. Discover more by getting in touch with a TTR Data Recovery specialist today.