RAID 0 array question.

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leggy

Guest
Old question that has probably been asked before but...


running a win2k system, can I stick in an identical hard disk to the one I have and build a RAID 0 array without fdisking and formatting?
 
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leggy

Guest
I knew that would be the answer and I also knew it would be you who told me :)

Thanks Emb.
 
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Mellow-

Guest
I don't know what a RAID is, but you can't use a drive till it's been partitioned and formatted.
 
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Testin da Cable

Guest
a simple [non tech] way to explain raid: it allows you to string multiple harddrives together into sets, or possibly one big drive. it has other bells and whistles too, but that is where it's at really.
 
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leggy

Guest
Originally posted by Mellow-
I don't know what a RAID is, but you can't use a drive till it's been partitioned and formatted.
Click to expand...

I know I had to format the new drive ffs :)

But I wanted to know if I could build a RAID 0 array without formatting my exisiting drive with all my goodies on it.
 
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Happy Go Lucky

Guest
It's only possible with RAID 1 I believe.

BTW RAID 0 feels a bit over rated (performance wise), however I have all the space to use, and I think if one drive fails, the other will work.
 
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smurkin

Guest
Thats right dude...you lose a stripe in RAID 0...you lose all data. What is more the remaining working drive cant easily be unraided...ie you gotta take it off the RAID controller if you want to use it again. And simply reformatting wont unraid it.

So backup or be dammed :)
 
M

Mellow-

Guest
Originally posted by Testin da Cable
a simple [non tech] way to explain raid: it allows you to string multiple harddrives together into sets, or possibly one big drive. it has other bells and whistles too, but that is where it's at really.
Click to expand...

What so like you could get three 20Gb disks and assign them all to a single drive letter?
 
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Happy Go Lucky

Guest
JBOD (Just a bunch of discs) I suppose it doesn't matter if the drives are the same model, like it does with RAID. It would make good use of your RAID controller, if you haven't got identical drives.
 
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smurkin

Guest
What so like you could get three 20Gb disks and assign them all to a single drive letter?
Click to expand...

Well you could...I think....two striped and one redundant (for backup)..I think ?!?

But the point is its a cheap way of making a very fast drive. The key word is cheap or "inexpensive" (hence the I in RAID). Ordinarlily, each drive is a bottleneck on its own. If you spread the same data over 2 or 4 (or 6 or 8) drives and each drive is going full belt then potentially you increase transfer 2x or 4x etc, respectively. In reality with two drives, ime, that is nearly achievable...ie. 2x transfer rate.

But RAID wasn't really designed for your home pc..but for servers and high end puters. And for that reason redundancy (or backup) is another and important option. RAID 0 (no backup) can work for your gaming machine and nearly double your game load rate (or more depending on how many mirrored drives; if you have the space)......but it needs constantly defragging and you might find it disappointing...most do. And you have to backup somehow coz a drive fail with RAID 0 is a colossal loss.
 
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kameleon

Guest
Originally posted by Mellow-


What so like you could get three 20Gb disks and assign them all to a single drive letter?
Click to expand...

Yes , you would have a 60 Gb disk
 
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Testin da Cable

Guest
or a 40 gig disk raid5. or a 20 gig disk mirrored, ie. raid1 with a hot spare, depending on the capabilities of your raid card. or indeed a 60gig stripe, raid0.

you can do all kinds of things with it, depending on what your hardware or software can do, mellow. on average the little ide-raid controllers in workstation mobos are fun to play with for higher performance: making a stripe set, or raid0, from say...two drives distributes the i/o load over both drives, and your os "sees" a logical drive with a size equal to the sum of both drives. downside to the speed is that if one drive fails all is lost, so you will have to make backups. the average built-in raid chip can not add or subtract a drive to a set once the stripe is made.
it's called a "stripe" because, while your os just writes data to the logical drive, the controller splits it into chunks defined by something called "stripe size" and writes it across all the drives of the array until done. the actuall size of the stripe is a dark art in itself, and there are differing methods to get the correct one.

another option with our mobo-raid stuff is that we can make a so called redundant array, which in ide land means a 'mirror' or raid1. nearly nobody I know does this, because you have to use two disks for every logical drive. what the chip does is duplicate [or mirror] all the data to both drives. what this means is that were drive A to fail, you will have a complete copy on drive B and thus do not have dataloss.

I won't go in to details about "higher" raid levels, because only the most expensive ide solutions support them, and I gather you aren't talking about scsi (most scsi raid cards support tons of options, but again there is a quality curve). There is also a little something called LVM, or logical volume manager (aka software raid) and I'm not going to talk about that at all even though I use it myself and it's cool :)
 
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Scouse

Guest
(Not read all the thread)

But unless you're after fault tolerance (mirroring) then there's fuck all point using IDE raid unless you're using at least 4 drives....

Performance gain is just not worth it....
 
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Testin da Cable

Guest
funny you say that...I get uber performance with a 2-drive stripe. wouldn't mind checking out one of the big 8 drive escalades or that adaptec thingy tbh :)
 
T

Testin da Cable

Guest
more = better though. tip: if you're going to raid get a good card. as good a card as you can find.
 
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Happy Go Lucky

Guest
Originally posted by Scouse
(Not read all the thread)

But unless you're after fault tolerance (mirroring) then there's fuck all point using IDE raid unless you're using at least 4 drives....

Performance gain is just not worth it....
Click to expand...

Logic dictates that you will need a tower case as well, so those 4 drives have room to breathe.
 
D

Dimebag

Guest
The limitations of the array are down to your raid controller.

In a normal ata raid situation, say using a highpoint onboard controller or an add in card you could only have 2 disks in a raid 0 array, I dont think it lets them span over multiple channels.

You can use raid 0 and 1 at the same time and have 4 disks, but thats still only the same size as two together as one pair of disks are just a mirror image.

If your controller supports raid 5, which i think is scsi only (dont quote me on that but I think so) the min number of disks you can have is 3... and im not sure about the max. The reason being one drive acts as a parity drive for the other striped drives so data is not lost if the array goes down. The faulty disk can be replaced and the data regenerated, quite fancy!

Also in reply to the last couple of posts... the reason scouse said that unless you are using 4 drives, mirroring is not worth it, is because this actually implies that you have a 2 drive stripe array... 2 disks are just for backup. You dont actually get any performance enhancements using raid 1 anyway, which strikes me as quite obvious :)

Dime
 
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Embattle

Guest
Originally posted by Dimebag

If your controller supports raid 5, which i think is scsi only (dont quote me on that but I think so)
Click to expand...

Sorry but I had too ;)

Highpoint recently added a BIOS update (3.01) to the RocketRAID 404 card, which I have, that now adds RAID 5 support :)
 
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Testin da Cable

Guest
and adaptec and 3ware do it too. also with the big multichannel SCSI raid adapters you can plug in a serious amount of drives, 21 or more iirc. you could also get a dedicated drive array and plug in a fiber based controller...but that's a wallet thumper heh.
 
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