RAID Questions.

RAID + Me =

Hey, So these questions pertain more to RAID for Desktops as Im trying to build my own right now, but the questions are pretty basic and (hopefully) the answers wont be affected whether its RAID for a notebook or Desktop.

So my quesitons are:

1. What is RAID? what are its advantages if I had 2x of this HDD

http://www.newegg.com/product/product.asp?item=N82E16822144701

2. How would I know if a RAID part is compatible with that (or any hdd)?

 

RAID is usually used for redundancy, if one drive fails there's another drive that takes over (this is one version of RAID). Most commonly used by average users is RAID 0 and/or 1. One of them (I keep forgetting which) simply is a mirror drive config. When something is installed like Windows, a game, something downloaded, whatever, both drives get installed with the same data so the data is written twice, one for each drive. This means that you have an active backup drive so whenever one fails, the other keeps going and has up-to-date data. This config can be slow cuz both drives have to be written to. RAID 1 uses both drives but not as mirrors, it uses them almost like they are a single drive, so pieces of data are written in each drive, neither drive is a whole drive but part of a virtual drive that contains both spaces. This is a faster config but offers no fault tolerance, so if one drive fails, you only end up with the partial data you have in the other drive, not a complete backup.

as for compatibility, you could check the sites of the RAID chipset you have, but most drives should be compatible though I have seen some that aren't depending on the chip and the drive model

 

Check out entry on Wikipedia.

RAID basically offers quite a few different options depending on how you set it up. You can make a bunch of different HDDs look like a single unit, you can set up various levels or redundancy/backup.

You will need some sort of RAID controller to make use of it.

If you had 2x of that HDD, you could make it appear to be one huge disk, split the data across them various ways...really, the best way is just to read the link, it explains the various raid 'levels'.

I'm not 100% sure, but I believe that most/all modern drives are RAID-capable.

 

Let me answer your second question first as it is easiest.

Yes, those HDs are RAID compatible as are any SATA drives. What counts is if you mobo is compatible. If you are looking at the one recommended to you on your other forum ( GIGABYTE GA-965P-DS3 (rev. 1.3)), you can run either RAID 1 or RAID 0. All you will is have to set it up. Also, FYI, I have run the same HDs you have in RAID 0, RAID 1, and RAID 10 without issues.

Now, you first question could give you a length answer, let's see if I can sum up. As vespoli said, check wiki for really good information.

RAID 1
This will use two identical hard drives that will be mirrors of each other. In other words when you write to one drive you will right to the other. If one drive fails, you won't loose your data. You can plug in a new drive that will re-create the redundancies so you RAID will be running again.

This type should be used if you are concerned about you data. It is also possible to get quicker read speeds if your controller can read both drives at once. Also, since the drives are mirrors, you will only have a total HD size of one of the drives. So if you have 2 x 250GB HDs, you will have a total size of 250GB.

RAID 0
This can use two drives or more (the mobo mentioned above will only support two I believe). Essentially, data is written and read from both drives simultaneously in chunks. Some data goes to one HD, and some to the other. The total size of this drive will be the size of one HD x2. So if you have 250GB, it will be around 500GB. ou will get slightly faster read and write speeds in this mode, not as significant as you may think though.

The problems with this set up is that is you lose one drive, you loose all your data. I would recommend against this mode if you have important data.

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This is a really really brief overview of what you can run with most motherboards these days. Having run the different modes, I would say stay with RAID 1 if you are going to RAID. Data redundancy is nice. If you run RAID 0, make sure that you have another drive to back that data up to in the event of a crash.

Hope that helps! Good luck!

 

oops got them the other way around hehe

there was also RAID 1.5 which was supposed to be a combo of RAID 0 and 1 i think.

 

I have been enlightened. haha. thanks for the answers.

but if all it will do is either mirror or connect the drives then I can save my money for other things. (i dont really have a need for either of those uses)

In fact on my older desktop I ran an 80gb for my OS HDD and a 250gb for media and data and that way i could play around with software and things on the 80 while keeping things safe on the slave.

 

You are correct, but it is called RAID 10, or RAID 0+1. You need four hard drives to run this mode, not to mention a comparable motherboard or RAID controller card. I ran it off my motherboard but had some issues with it. I would reccomend having a controller card to run RAID 10.

Yup, RAID is not a necessity, it is a personal choice. I like RAID 1 because I don't ever have to back up. It is always done automatically every time I save something. I have lot of important data, and the redundancy gives me a sense of security.

If you don't think you need RAID, you don't. Its all up to you in that regard and how you want to save and store your data.

 

Many people think RAID-5 is the best type of RAID, because you get insane performance AND the ability to back up all your data. The only problem is that you need 3 identical hard drives to do it, and most people don't have that kind of money.

 

Plus not all mobos support RAID 5, like the one he is looking at, and controller cards are very expensive. But RAID 5, like and RAID has its issues. I have read that you pretty much need a dedicated controller card because the parity calculation are very taxing on system resources.

 

Really? I've got a RAID5 software array running on my media center, and it still runs great, with a lowly Athlon 2400+. But that's under Linux. Almost fast enough to even decode HD video

BTW, the word is "lose". You lose a game, your belt comes loose. It's a common error, but it just bugs me to no end when I see it Nothing personal.

Anyway, I would recommend either not going with RAID (just use it as two drives, C: and D: or whatever, since you're probably going to use Windows), or going with RAID1 if you want protection from a drive crash.

 

Perhaps I am wrong then. Just something I remember stumbling upon when reading about RAID setups.

I fixed that little spelling error for you. Not sure why I did that. I realize it doesn't make sense, lol.

 

Yes well I think there is a difference between hardware and software RAID 5

I once considered RAID back in the Nforce2 athlonXP days but decided against it cuz the motherboards I was looking at had either hard drive compatibility issues or were ridiculously slow (an old NF2 Gigabyte mobo that was)

sometimes its just not worth the hassle

 

RAID-5 doesn't give you "insane performance". At best, it's on par with a single drive. It's also more complex than RAID-1, and if a drive dies, it takes more time/work to recover your data. (Of course, it can still be done, which is the main thing, but it needs a good chunk of time to fix up the disk array)

Btw, I lost a harddrive a week or so ago. Luckily, it was in RAID-1, so I just disconnected it, and was able to continue running with all my data. So yeah, RAID-1 for me. 5 works too, if you have lots of harddrives, and don't mind some downtime if/when a disk dies.

But as said above, don't bother with RAId unless you know you need/want it. If you're not sure, there's no point

 

Please help educate me. What's with the fuss over Raid 5? I thought that Raid 0 was the fastest and greatest thing out there. Is it really that much more risky in laptops? Does the risk increase per the number of drives configured to Raid 0?

So if one of the hard drive fails, I assume that the other two will still work as well correct? If that's the case, then supposing you have 3 X 100 GB in RAID 5. Now suppose you've used up 250GB total. Does this mean that 50GB of information is lost?

Also, if there is no speed advantage of RAID 5 over a single drive, then what's the point of RAID 5, wont you be better off just having no RAID at all?

 

You can only have two drives in a RAID 0. And the risk is fairly easy to figure out. You have two disks. Two disks have twice the failure rate of one disk.
If one fails, *all* your data is gone forever. That's the entire point in RAID 0, it's not to keep data safe, it is to boost performance (in some specialized cases), and, well, to sound cool, because the enthusiast community has caught on to the idea that RAID 0 is leet...

As such, RAID 0 isn't really RAID at all. RAID (Redundant Array of Independent Disks) is about redundancy that is, if you lose a disk, your data is kept safe because you have one or more extra disks connected that can take over.

RAID 0 is, from a RAID point of view, an abomination. RAID has nothing to do with performance.

About RAID 5? That is true RAID. The idea is that you connect X harddrives, and get X-1 harddrives' worth of free space. 4 400GB disks will give you 1.2TB available disk space.
And because of the way data is stored in RAID 5, any one of the disks can die, and you'll still be able to retrieve *all* your data. It'll then take ages to rebuild the array, and of course, if a second disk dies before you've replaced the broken disk and rebuilt the array, you're screwed. But one disk can die and you'll still have *all* your data. That's the point of RAID 5.

RAID 1 is another form of "true" RAID, that is, one that offers redundancy rather than speed. This uses exactly two drives, which are kept in sync, so each disk's content is an exact mirror of the other's. Obviously, that means that if one of the disks die, you have a 100% up-to-date backup on the other, and you can even continue running from that disk with no downtime.

So RAID 5's advantage is that it better utilizes the disk capacity (if you have 4 drives, you can get three drives' worth of disk space. RAID 1 would only give you two because the drives are paired and mirrored)
RAID 1's advantage is that it can continue running if a disk dies (where RAID 5 would be unable to do anything useful until the disk has been replaced and the array rebuilt), and because it's a much simpler setup, write speed is much better than RAID 5 (Or rather, write speed with RAID 1 is about the same as with a single drive, while it's significantly worse with RAID 5)

And RAID 0 is an entirely different beast. Instead of offering data redundancy, it *increases* the chance of data loss.