Can someone please explain RAID to me?

mickledore

mickledore

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My laptop died a slow lingering death, so I've just taken delivery of a PC to replace it.

This is specced with a 120GB SSD and two 1000GB hard drives in a RAID 1 Configuration.

When I look in My Computer I see my C Drive at 111GB with 84.5 GB free. I presume this is the SSD. There is also another drive New Volume(I) at 931GB totally free.

I can't see my two hard drives anywhere.

If I go into Control Panel>Devices and Printers I see Mass Storage Device. When I open this up I see loads of things, principally E, F, G & H drives as portable devices. I'm a numpty with this new system, so I've no idea how to locate, or use my hard drives. I've tried loading just a couple of pictures from my backup, but they are shown as being on the C drive.

Am I right in thinking that the I drive is the two hard drives linked together somehow, but how do I store anything on there? I'm not seeing that drive shown as an option.

I'm stuck! Can you help a numpty?
 
If your hard disks are in a RAID 1 config you'll only be able to see the RAID volume. Which it sounds like you can. With RAID 1 half of the total space is used for redundancy so 1tb drive + 1 tb drive will leave you seeing one volume of just under 1tb
 
Thank you. That introduces another term that is new to me. What is redundancy, and how is it used?
 
Redundancy = your contigency capacity. It's redundant until you have a primary disk failure and you need it to use it.
 
RAID 1 means that all data written is mirrored (duplicated) on both disks.

RAID 1 is usually used when reading data is more important than writing, as all writes happen twice and are therefore slower (but not twice as slow) then a single write. Reads are faster as data can be obtained from both disks as the same time.

Do you know if this a hardware or software RAID.

With hardware RAID 1 you have a single point of failure in the RAID controller, so if that goes then your RAID also goes unless you buy exactly the same controller and plug your drives in to it.

RAID 1 IS NOT BACKUP. You must also backup your data to an external drive(s).
 
To help you further.... with RAID 1, when your PC application writes something to the primary disk, the code contained within the RAID hardware will replicate that same write to the secondary disk. So your disks are mirrors of each other.

Edit: beat me to it above - agree with all of that.
 
Thanks guys. A lot of stuff there that is new to me.
I don't know if this is a hardware or software RAID. I have seen a message that says something like I have a fail safe on one drive( Sorry can't remember the exact wording).
Does this mean that once I have filled one drive then storage automatically moves to the second drive, or is it merely a fail safe set up?
Sorry for the questions!
 
If you fill the primary drive, your secondary drive is automatically full as well. You cannot start writing to the second drive as a primary.
 
Ah I see, I think. When was told that I had 2 x 1 TB hard drive, that didn't mean that I had 2TB of storage? I only have 1TB of useful storage. So what is the benefit of this set up?
 
It's a bit like having a spare drive and sending info to both at the same time.

In theory if 1 fails you should be able to recover your stuff from the other, that's the basic of it
 
The benefit is that, if your primary hard drive suffers a hardware failure, then your secondary drive will take over - otherwise you would have lost everything on the drive (and then had to restore from other backups etc that you should have).

You then have a windown of opportunity to go and buy another drive to replace the one that failed, fit it, and then your RAID configuration will be back in full swing.

As above, it is only there to protect you from hardware failure. If, for example, you corrupt a file on your primary disk, it will also be corrupted on the secondary - you MUST consider other backup options to compliment the RAID setup.
 
JohnnyJ said:
As above, it is only there to protect you from hardware failure. If, for example, you corrupt a file on your primary disk, it will also be corrupted on the secondary - you MUST consider other backup options to compliment the RAID setup.
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:agree:Ŷ.

This, I made the mistake a few years back, bought an Alienware with raid 0, thought great it's bullet proof, until drive fail, I dint realise or think to ask. (By the way raid 0 is different to yours )

Cost me hundreds to recover, Back up, back up, back up and just in case save again.
 
Thanks again. I do have external backup, two in fact. In effect what seems to be the case is that I've only got half the storage I asked for and thought I was getting. Grrr pesky salesman. My fault for being a numpty on geeky things
 
mickledore said:
Thanks again. I do have external backup, two in fact. In effect what seems to be the case is that I've only got half the storage I asked for and thought I was getting. Grrr pesky salesman. My fault for being a numpty on geeky things
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You might thank him one day !

Just about all businesses run their computers with RAID protected disks. It's normal !
 
Others can confirm, but you do have the drives, you maybe able to do away with raid, or change it to RAID 0. (Striped)


Anyone. ?
 
neil_g said:
Servers maybe, desktops not really.
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See what you're saying. The businesses I work with are quite large and their PC data drives are always on a SAN or NAS, RAID protected. Or the PCs themselves are virtualised........
 
scott199 said:
Others can confirm, but you do have the drives, you maybe able to do away with raid, or change it to RAID 0. (Striped)


Anyone. ?
Click to expand...

That thought crossed my mind too. But that will be sometime in the future. Certainly not before the warranty expires.
 
Changing raid levels really shouldn't affect warranty any more than formatting a hrs drive would.

Raid0 isn't really worth the risk (I.e one drive fails = data bye bye) unless you're running a real time backup/sync.

JohnnyJ said:
See what you're saying. The businesses I work with are quite large and their PC data drives are always on a SAN or NAS, RAID protected. Or the PCs themselves are virtualised........
Click to expand...

I guess it depends on the work being done. all of ours are users are encouraged to store data on shares off a San (general office staff and design suite of macs) :)
 
JohnnyJ said:
To help you further.... with RAID 1, when your PC application writes something to the primary disk, the code contained within the RAID hardware will replicate that same write to the secondary disk. So your disks are mirrors of each other.

Edit: beat me to it above - agree with all of that.
Click to expand...


Can I add at this point... that RAID is NOT back up. It's redundancy. It offers no protection against accidental deletion, or loss through malicious software, file corruption, or even theft of the computer.

You'll still need to back up your files if you use RAID.
 
Pookeyhead said:
Can I add at this point... that RAID is NOT back up. It's redundancy. It offers no protection against accidental deletion, or loss through malicious software, file corruption, or even theft of the computer.

You'll still need to back up your files if you use RAID.
Click to expand...

Indeed, as per posts #5 and #11 above. :-)
 
mickledore said:
Thanks again. I do have external backup, two in fact. In effect what seems to be the case is that I've only got half the storage I asked for and thought I was getting. Grrr pesky salesman. My fault for being a numpty on geeky things
Click to expand...

Take it back then, if you already have a couple of backups, it's the RAID itself that's redundant:rolleyes:
 
You can't stress important facts too many times. :)
 
No you can't. RAID is not back up!!!

[runs away]
 
Indeed.. but.. just having your stuff on RAID1 and nowhere else isn't. My back up server is RAID... but it's a back up server, not my main storage.
 
Have I got this right then? If I have my work backed up on (two) external harddrives, then I'm gaining little benefit from having two internal hard drives in a RAID set up?

If that's the case, then when I am getting close to filling one of my two internal hard drives I could look at undoing the RAID set up and effectively double my internal storage. Is that right, or more uneducated tosh from me?
 
mickledore said:
........I could look at undoing the RAID set up and effectively double my internal storage. Is that right...?
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Yes, if you 'de-raid' it you'll have two normal drives of 1000GB each.
 
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Ah, I see. That really means doing it now, but I wouldn't know where to start. Might have to forget that idea then.
 
To de-raid it shouldn't be that tricky. You'll need to find out if it's hardware or software raid though.

As Neil says - if you're going to do it, don't put any data on the raid disks.
 
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If you don't really understand, I would leave it, just in case.

Tbh external storage is so cheap, if you keep pics and video's externally, then 1TB. Should be loads for data and software
 
scott199 said:
If you don't really understand, I would leave it, just in case. .....
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As long as the OP doesn't do anything to damage the OS on C:drive (the 120GB SSD) I can't see what can go wrong. He could negate the risk by making an image of C:drive (using Macrium Reflect or similar) and storing it on one of the other backup drives mentioned in post 30.

Either way, the retailer/salesman shouldn't have used RAID without asking first - hence there's a case for taking it back and getting them to sort it out free of charge.
 
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mickledore said:
Have I got this right then? If I have my work backed up on (two) external harddrives, then I'm gaining little benefit from having two internal hard drives in a RAID set up?
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It will depend on the completeness and timing of your other backups.

Example: Your normal backups take place daily at 5pm. At 7pm, you post process 50 photos. The next morning, you write 30 pages of your new novel in Word. Then update some important spreadsheets for your business (you are a busy guy). At 3pm (that next day) your primary disk fails completely, and all data on that disk is lost. If you have RAID, you will continue working (almost) as if nothing has happened. If you don't have RAID, you have lost all of the updates/creations that you did since 5pm the day before.

Disk is cheap as chips now and if you've been provided with a RAID PC, I'd stick with it.
 
Thanks again. I certainly won't be changing anything soon. I want to see how things pan out before taking any rash steps. As you say disc space is cheap so storage should present no problems.
 
mickledore said:
.... I certainly won't be changing anything soon. ......
Click to expand...

It's still a good idea to use Macrium Reflect to make an image of C:drive (and store it on one of the external drives) - it'll get you out of trouble if your SSD fails and will avoid having to reinstall your OS and programmes on a replacement SSD.

The free version is here: http://www.macrium.com/reflectfree.aspx.
Help files here if you want to read up on it: http://www.macrium.com/help/v5/reflect_v5.htm.
 
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