You've Installed Dell PERC RAID, But the Controller Can't See and Use the Installed Hard Drives!

This issue can cause support workers to grow a lot of gray hairs. Everything might look perfect, but for some reason, it’s not working. When you boot the server, there doesn’t seem to be a problem – until the disks don’t spin and there are no indicator lights to be seen.

How can you avoid this headache? Check the carrier frames. Make sure the hard drive is in place properly. If there’s no connection between the hard drive and the backplane, there might as well be no hard drive.

This issue can cause support workers to grow a lot of gray hairs. Everything might look perfect, but for some reason, it’s not working. When you boot the server, there doesn’t seem to be a problem – until the disks don’t spin and there are no indicator lights to be seen.

How can you avoid this headache? Check the carrier frames. Make sure the hard drive is in place properly. If there’s no connection between the hard drive and the backplane, there might as well be no hard drive.

RAID

A RAID (Redundant Array of Independent Disks) is simply a group of physical disks that provides high performance by multiplying the number of drives used to save and access data. A RAID subsystem improves I/O and data availability, as well as data storage and fault tolerance. However, keep in mind that RAID shouldn’t be used as a backup solution (and we’ll talk more about backup later!).

RAID subsystems can be implemented with either hardware or software. A system using hardware has a DELL ERC RAID Controller that implements RAID levels, processes and reads the data, and writes it to the physical hard drives. When using basic software RAID, the operating system implements the RAID levels, so using software RAID by itself can slow system performance.

Is RAID the First Level of Data Protection?

If we believe that data loss can be covered by rectifying the hard drive failures by rebuilding the missing data from the remaining physical disks, RAID is only one building block in the grander scheme of data recovery. In accordance to our thoughts and beliefs, data loss can be covered because we have rectify the hard drives failures by rebuilding the missing data from the remaining physical disks containing data or parity.

RAID is only one building block, a brick among the walls of data recovery scheme because it cannot replace a backup plan.

Most RAID levels are strong, and they can protect you against data loss and help in recovery from hardware defects, but what they can’t protect you from is data loss from sources outside the system – such as fire, water damage, or theft. They also won’t protect the system against soft errors, such as user error, software malfunction, and malware infections.

So, if you want to include RAID as part of your data protection plan, that’s fine. But, remember, RAID is only the first level of protection. You’ll need more than that to keep your data safe.

Which RAID is Right for You?

Are you using a RAID for performance, for fault tolerance – or for both? Are you implementing a RAID with hardware or software? These are important questions to ask when choosing the RAID that’s right for you.

Software supports fewer levels than hard- ware-based RAID. Most hardware-based RAID controllers have battery backup, but different controllers have different proces- sors, cache memory, and support different levels of RAID.

RAID Levels and What You Can Use Them For?

RAID 0 is also known as “disk striping.” With RAID 0, data is written across multiple hard drives, meaning that the computer’s work is handled by multiple disks, which increases performance. A minimum of two hard drives is required for RAID 0. What’s the downside? There’s no fault tolerance; if one disk fails, the entire setup is affected, upping the chances of data loss or corruption.

RAID 0 is ideal for things like image retouching or video editing – working with data that has to be read or written at high speeds.

RAID 1 is also known as “disk mirroring.” This a fault-tolerance configuration where data is cop- ied, or “mirrored,” from one hard drive to another in real time. If one hard drive fails, the other will keep working. This is a relatively low cost con- figuration, and it’s one of the simplest ways to improve fault tolerance. Unfortunately, there’s al- ways a downside. RAID 1 causes performance to drag slightly, and it halves disk capacity.

RAID 1 is ideal for critical storage, such as in accounting systems, where data storage is vital. RAID 1 is also good for small servers that only have two hard drives.

RAID 5 is, for business servers and enterprise NAS devices, the most common RAID by far, providing better performance and fault tol- erance than disk mirroring. With RAID 5, data and parity are striped across three or more hard drives.

If a hard drive starts to fail, data is recreated from the distributed data and can eventually be rebuilt to new disks when fail- ing disks are replaced. The downside to RAID 5 is that servers that perform a lot of writing will take a performance hit.

RAID 5 is ideal for file and application servers with a limited number of data drives, mixing efficient storage with strong security and good performance. It’s a balanced system that gives you the best of both worlds.

RAID 6 is identical to RAID 5, except it uses an additional parity block. Because of this, your system will remain operational even if two disks die.

RAID 6 is ideal for the same uses as RAID 5, except it’s better for servers that use many large drives to store data.

RAID 10, often referred to as RAID 1+0, is a combination of RAID 1 and RAID 0. RAID 10 gives the best performance, combining the mirroring of RAID 1 with the striping of RAID 0 – but you’ll be paying more for great performance, because RAID 10 requires twice as many hard drives as the other RAID levels. RAID 10 can be implemented as hardware or software, but a lot of the performance ad- vantages are lost when you go the software route.

RAID 10 is ideal for heavily used database servers or servers that are doing a lot of writ- ing. It’s both secure because it mirrors your data, and fast because the data is striped across multiple disks.

Whatever You Do,
Remember to Back Up Your Data!

Again, RAID is only the first level of protection when it comes to keeping your data safe. No matter how big or small your company is, or even if your computer is only for personal use, there’s no technological mishap worse than the irrecoverable loss of data.

Data backup has always been a vital issue in the world of technology, and it’s come a long way from being limited to physical devices like floppy disks, CDs, thumb drives, and external hard drives. Now, we have cloud storage. And as the popularity of cloud storage increases, you have a choice to make – should you back up everything through cloud storage, or do you store data locally?

When Backing Up Your Data, Use the 3-2-1 Rule!

The 3-2-1 rule is pretty simple: have at least three copies of your data, keep those copies on at least two different types of storage, and have at least one of those copies offsite. For example, if you have a file full of irreplaceable family photos, have three copies of that file. You could put one copy on a flash drive, back the photos up to the cloud, and keep another copy offsite.

The 3-2-1 method is cost-effective, flexible, and gives you easy access to your files. If your system fails, don’t worry! The 3-2-1 rule is now widely hailed as an industry best practice. This rule states that you should have three (3) copies of your data at all times, that you keep it backed up on at least two (2) different types of storage, and that you have at least one (1) copy of the data offsite.

However, even the best plan has disadvantages. Depending on what backup methods you use, the 3-2-1 system might not be the fastest way to recover your files. There’s also some security risk involved with putting your files in cloud storage and having offsite cop- ies. But, in this case, the benefits of backing up irreplaceable data might just outweigh the risks.

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