I keep hearing from people in tech communities that keeping things in RAID is somehow better than just slapping it on a hard drive backup, but… why? What even is RAID storage and why is it better?
I spent last night looking up RAID servers on Amazon to get me an answer but I left with more questions: Do all the hard drives in RAID need to be the same size? My entire family switched their laptops due to the work from home orders, so I have a bunch of unused SSDs and HDDs lying around the house, can I just throw those in a RAID server and have it work?
Can I install an operating system on a RAID server? Would it run faster/slower? If I have a MacBook and can install Windows on my RAID server, would it work a bit like bootcamp? What happens when I’m not connected to it?
I HAVE SO MANY QUESTIONS!
EDIT: I think I get it now: It’s a system that’s automatically backing itself up to… itself essentially. You do this by creating redundancies within the RAID system (multiple SSDs). If that’s not it, please tell me.
So final question: can I use a RAID server NOT in RAID? As in can I put multiple hard drives in a server, then plug the server in to my Mac and have it appear as several individual drives? Almost like a HDD mounting system on steroids.
In: Technology
RAID is just a way to use several HDDs together.
It has nothing to do with backup.
RAID is not a form of backup! (This is a vitally important concept to grasp and has ended the careers and business of a number of people who had not fully internalized it. RAID by itself is not a backup solution!)
What RAID is, is a way to use two or more physical drives together in a way so they appear as a single drive to the computer and provide some level or redundancy and increased performances (in some versions at least)
There are several schemes of RAID which usually are labeled with numbers RAID 0 , RAID 1, RAID 5, RAID 6, RAID 10 etc.
The simplest version is RAID 1.
RAID 1 is just two drives together which both have exactly the same contents.
Every time you write something to a RAID 1 drive you write it to both drives at the same time. You can read from either drive. If you set things up right you can actually read both drives at the same time (different info from each) doubling your read speed compared to normal drives.
If either drive fails the dat will still be there on the other drive. This is what we call redundancy (the R in RAID)
The next most common scheme is RAID 5. it uses three or more drives. It distributes the data across the drives in such a way that even if one disk fails you still have all your data.
You can have half a dozen disk together in a RAID 5 array and they will appear on the computer as a single drive. The capacity of the drive will be that of all the drives together minus one.
RAID 6 is the same but instead of having just one disk or redundancy you have two, meaning that you also loose the capacity of two disk from your total. It is worth it in some occasions.
RAID 0 is not really a RAID at all. because it doesn’t provide any redundancy. It just puts a number of different disks together and presents them to the computer as a single one with the capacity of all the drives combines.
If any single drive fails in a RAID 0 all your data is lost.
It may be useful if you don’t care about preserving your data and just need some place to temporarily store huge amounts of data cheaply and with high read and write speeds.
RAID version with double digits combine the above concepts. RAID 10 is RAID 1 + RAID 0 for example.
The important hing is that all of the above is just describing how disk drives are connected to a computer. Nothing else.
You can use you standard windows desktop PC put two or more drives into it and configure them so the computer treats the RAID array as a single drive for example.
There are ways to do that in the operating system itself or by using dedicated hardware. The hardware part means that it won’t take resources away from the OS to decide where to put which data.
You can build or buy a computer which does little else but run an array of disks in a RAID and presents them to the outside world as a fileshare or similar. This is called a NAS. The NAS doesn’t need to use RAID technology but could always present each individual disk to the outside as a different network share. This is not a good idea.
There are other devices that don’t show their array to the outside via network technology but use the same sort of storage technology that computers use to connect to drives internally. These type of SAN solutions can be quite expensive and are usually only used in professional environments.
In recent years RAID has lost some of its importance. They were originally invented because they allowed you to use s a number of small cheap drives as a single big one that was fast and unlikely to fail completely and destroy all your data.
Over the last few years SSDs have become reasonably cheap and quite big by themselves. Operating system like Windows have built in ways to access and divide up drives that are more flexible than traditional RAID and in enterprise environments new technologies have found hold.
But to repeat myself don’t think of RAID as a from of backup!
You can put your backups on a RAID. That is a good idea. However if you are running your computer on a RAID directly you may have redundancy in case a disk breaks, but that is it. If you accidentally delete something or catch a crypto virus it will destroy all redundant copies of your data across the RAID.
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