Hello, everyone!
I would like to share with you an
article about the need for Redundant Array of Independent Disks. For this basic example, we use the HDD as our building block.
Data is stored on HDDs on which data can be read and written. Depending on the methods that are used to run those tasks, and the HDD technology on which the HDDs were built, the read and write function can be faster or slower. The evolution of HDDs is incredible. We can store hundreds of gigabytes on a single HDD, which allows us to keep all of the data we can ever imagine.
Even though this approach seems to bring us only advantages so far, one question might be what happens if for any reason we are unable to access the HDD?
The first solution might be to have a secondary HDD where we can manually copy our primary HDD to our secondary HDD. Immediately, we can see that our data is safe. But, how often must we run those manual copies if we expect not to lose data and to keep it as up-to-date as possible?
To keep it as current as possible, every time we change something, we must make another copy. But, must we copy the entire amount of data from one HDD to the other, or must we copy only what changes?
Fortunately, technology exists that can help us. That technology is the Redundant Array of Independent Disks (RAID) concept, which presents a possible solution to our problem. It is clear that data needs to be copied every time that it changes to provide us with a reliable fault tolerant system.
It is also clear that it cannot be done in a manual way. A RAID controller can maintain disks in synchronization and can also manage all of the writes and reads (input/output (I/O)) to and from the disks.
Typical RAID scenario
The figure shows the diagram of our RAID system. The A, B, and C values in the diagram represent user data, such as documents or pictures.
This type of RAID scenario is known as RAID 1 or a mirrored disk.
Stand-alone disks provide the following advantages:
Redundancy to disk failure
Faster reading of data because the data can be read from either disk
Stand-alone disks provide the following disadvantages:
Slower when they are writing because data needs to be written twice
Only half of the total capacity can be used
Thank you for reading. You're welcome to leave a message and exchange in the comment area!
