Introduction to RAID

Hello everyone, In this section will discuss about the raid, what is raid all about, why it is important to configure raid in your environment, what are different types of raids and how to configure raid, what are the commands for that? So all those things we are going to discuss in this section, will have theoretical session and then will move towards the lab session so that you can easily understand the concept of raid. so lets start, Raid stands for a redundant array of inexpensive disks which was later interpreted to redundant array of independent disks. So this is the full form of raid This technology is now used in almost all the IT organizations looking for data redundancy and better performance and in simple words, raid is used for data redundancy and better performance. It combines multiple available disks into one or more logical drive and gives you the ability to survive one or more drive failures depending upon the raid used. So in simple words, let me take an example to explain you. So I'm moving towards my blackboard. Suppose I have one server this is my one server, in my organization I have one server this is my server A and I want to host some application suppose I want to run an application. This one. This is my CFS application. This is very critical application. So to run this application, I need some storage. So for example, I need 500 GB storage. So one way to get disk suppose I have this is my physical disk. This is my physical server say for example, if it is a physical server, obviously there would be some array This is a disk array Right, which is physically connected to your server Right? in that array, you can see that a lot of disk are connected. This is my first disk. This is second disk, third disk four disk, five disk suppose In my array, I have ten disk are there I'm just taking an example of physical server, this is my physical server Right? and I want to run an application that is cfs application, which is a very critical application. And one internal storage disk array is connected to my this server Now all this disk are visible to the server. System admin can see all the disk. I want to run this application. Obviously, I need this storage The storage is already there. suppose, the size of each disk is 100 GB So obviously 1000 GB That is 100 plus 10 times. So thousands GB of disk is available. Space is available on my server and I have hosted I was started configuring this application using this space. Right? my application is running fine, but suppose any of my disks say for example my first disk on faulty or my third disk on faulty. It could be possible because these are physical servers. Anything happen to the box. Any hardware issue comes at any time if any of my application goes down. So what will happen? My this critical application, which is very critical application, will be affected. Right? so do avoid this. What we can do, we can configure the raid, the different types of raid that we discussed. So with the help of raid what we can do, we can combine that number of disk Suppose I have taken these ten disk and I've taken the five disk, say for example and I've created a one logical drive. Right I have given the name A This is my logical drive and the size which I'm getting at the server, say for example I have used eight, five, i have used I'm getting 700 GB space and 32 GB space for the redundancy purpose of the parity purpose. Now, this logical drive which is available on my physical server, I've configured to raid that is raid five or whatever I have configure, Each raid having its own meaning we will discuss all raid. So with the help of raid if any of my disk gone faulty even though I'm able to access my disk. So that's the benefit of the raid and that is important. So in simple words here, if I'm reading again here, you can see that it combines multiple available disks into one or more logical drive. So at the back end you have the disk. But at the server end I have created a logical drive with the help of raid and that gives you the ability to survive one on more drive failures. So it means that if any of the disk, one or two gone faulty, even though your data is not affected it is still your application is still available. So that's the benefit of your raid, here Again, coming. Suppose this is my virtual server This is the physical server, but I do not have this disk array connected. I have taken the space fromSAN storage Suppose this is a SAN storage. It could be HP. Whatever company you have and from that storage I have asked the storage team to allocate some storage to my server, suppose they have allocated five hundred GB I want to run my application CFS application. I do not have any disk storage is connected to my server So in that case, I should have some like drive , cards These are my FC cards or hba cards With the help of hba card, we can access the san storage. Now, with the help of these hba cards, I have asked the storage team they have joined the storage and after that I can see that disk is available on my server. Right? now at the storage end and mostly the storage team, They are using their own rates if they are giving one disk and the size of the disk is 500 GB., so obviously the storage team are their end, they're using some raid because now is storage team responsibility Whatever the disk I'm giving to the server team, it should be properly redundant. That's why we have seen that whenever we are getting the storage from the storage team, it never goes down. There is a very less possibility, even though if you are getting this disk at your end , you can configure the raid on your server as well, that is called the software raid So we will discuss all those things. So I'm just trying to give you a brief introduction about the raid. The raid contains the group or set of arrays That is the set of disk. A combine of drives makes a group of disk to form a raid array or raid set . It can be a minimum of two disk connected to the raid controller and make the logical volume or more drives can be in the group. So in simple words, if you want to create the raid, then at least you need two or more disk Only you would be able to create the raid right. Only one raid level can be applied in a group of disk. Right. If you have three disks so you can apply only raid one, zero or five or 10, whatever, but if a disk is already applied for the raid, the same desk cannot be applied for some other raid. Right? Raid can be used when we need excellent performance as well. So we'll discuss all those things in the details as well. So friends that's all for this lecture. We'll see in the next lecture. Bye bye, I take care.