several questions about RAID 0

[olson]

If only one drive shows up to Windows and is roughly twice the capacity of one of the disks, its probably working. Not sure what you mean by horror stories of failure, but yes, disks fail and often they fail catastrophically without warning. In a RAID array without any redundancy like RAID 0, a single failed disk means everything in the entire array is lost. The more disks in the array the greater then chances are for total data loss.

Generally speaking RAID 0 should only be used in situations where the data is already backed up elsewhere or is expendable. If you don't have a backup strategy and don't want to lose data then RAID 0 is probably not what you want to do with your disks. Cheers!

[Jettatore]

"In the unnalocated space I have about 1700 gb of space...roughly twice as much as I should have if the two drives were one entity"

Raid 0 is used for speed. You won't loose much if any storage using Raid 0. If you were looking for "redundancy" then you don't want to use Raid 0.

"what's up with all those horror stories about complete failure?"

HDD's use moving parts, and can fail in various ways. As of recent years the stability and reliability of HDD's has improved greatly. However, if you aren't using a redundancy mode array, and are using Raid 0 for speed only, if just 1 of the drives fails then the entire array will be rendered useless so your doubling your chances of failure as well data recovery may become more difficult.

I've had Raid 0 arrays fail on me in the past, and I've had regular drives in the past fail. However the disks involved were all tied to one line of disk drives and the well known company who made them lost a class action lawsuit do to the situation they put many of their customers in and have since moved out of the HDD business entirely. I haven't had an issue with a HDD before or since.

[ddg]

I just built a computer using a raid 0 set up, and it is working great. I only have 2 hard drives so it is not that big of an arrary, and I did buy server grade hard drives. I passes on the sale of the week at new egg because of my concern of a HD failing. I also have the capacity to add 4 hot swappable HD, and I will be saving my work there when I have had time to learn Maya better! I am extremely pleased with the speed.

PS: My 4 hot-swappable hd's will not be used in my raid 0 config....

[Srek]

You mixed up RAID 0 (striping) and RAID 1 (mirroring). RAID 0 will give you speed and the combined capacity of all drives, RAID 1 will give you security (and a bit of speed) but only half the combined capacity of the two drives.
I heavily recommend to not use RAID 0 for a system drive, it's even worse for an unbackuped data drive. The risk of losing everything due to a harddrive failure roughly doubles with RAID 0.
The reason ahy you did not need any drivers is that Windows 7 comes with a number of standard drivers for this, it's recommended to get the latest fully matching drivers though.
RAID 0 is best used as a scrap drive when you need a lot of space at high speed but you can afford to lose the content if anything goes wrong.
RAID 1 (or in many situations even better RAID 5) is recommended for security and speed.
There are many additional combinations of those three basic modes.
Over the years as an IT professional i had several occurences of HDs failing, often enough in stripsets. In by far the most cases those were RAID 5 setups i installed for customers and i only had to replace a disk to make everything work ok again. RAID 5 saved quite a lot of money over the years.

Cheers
Björn

[Leionaaad]

I didn't mixed up. I knew why I chose raid 0. For the moment I continue like this, I have an external drive to keep backups of the important stuff.
What I don't understand, why shows me the twice the space I actually have? how do I use striping, if I have all that space available??
Probably I will buy one more drive then, to have it in raid 5, or something. A few months I have to go with these tough.

Can somebody clear me out on the available space issue? Do I have 2 tb of actual space or not? (2 hdd's, 1 tb each)

[Srek]

If you use RAID 0 you get two times the capacity of the smallest involved drive (in your case 2TB). If you use RAID 1 you get the capacity of the smallest of the two involved drives (in your case 1 TB). If you choose RAID 0 on buildup (not JBOD), you already have striping set up, thats what RAID 0 is about.

Thats what i meant by you mixing things up, you created a RAID 0 but expected it to behave like a RAID 1.

Cheers
Björn

[Leionaaad]

oh brother....
I am more in the dark than ever before.
Let' sum up what i know from the manual and various places:
raid 0: striping. data gets written partially on both drives, for speed reason. if one drive fails, everything is gone.
raid 1: mirroring. everything gets written twice. if one fails, you can replace it an keep going.
raid 5: this one is like raid 0, only it has one more drive for parity(minimum of 3 drives).

now. I have raid 0. the manual says, this is for speed. I expected to have 1 Tb. I 2 Tb. How come? In the end i'll have space for 1 Tb or 2 Tb??

I don't get it, and obviously I should have ask a lot more questions BEFORE actually buying these things.

[Srek]

If in doubt ;)
http://en.wikipedia.org/wiki/RAID#Standard_levels

raid 0: striping. data gets written partially on both drives, for speed reason. if one drive fails, everything is gone.
Correct, and since both drives are used you get the added capacity of all drives.
raid 1: mirroring. everything gets written twice. if one fails, you can replace it an keep going.
Correct
raid 5: this one is like raid 0, only it has one more drive for parity(minimum of 3 drives).
Complete BS except for the minimum of three drives.
The data is stored in stripes over all drives as is the parity information. That way you loose the capacity of one drive (not one specific drive but over all the capacity of one) but it's safe against the loss of any single drive.

Cheers
Björn

[Remoth]

in Raid 0, you still have the combined storage of both drives, you just write half of each file to each drive at the same time, thus doubling the speed theoretically.

in Raid 1, you would have the storage of the smallest drive you use, since it copies the files to both drives, it treats it as one drive with a backup copy. so if you had 2 1TB drives in Raid 0, you would have 1TB of storage with a backup.

[imashination]

As simply as I can muster:

RAID 0
---
2+ drives
Extremely fast reads, Extremely fast writes. More drives makes it faster
More chance to lose all data as the number of drives increases
Offers no safety, if a drive fails, you lose everything on all drives
2x 1TB drives = 2TB of storage, you lose no space
Works fine with onboard RAID chipsets


RAID 1
---
2+ drives
Fast reads, normal writes. More drives make reading faster
Offers lots of safety, everything is saved to 2 drives
2x 1TB drives = 1TB of storage, you lose half your space
Works fine with onboard RAID chipsets


RAID 10 or 01
---
4+ drives
Very fast reads, very fast writes. More drives make it faster
Offers lots of safety, everything is written to 4+ drives
4x 1TB drives = 2TB of storage, you lose half your space
Works fine with onboard RAID chipsets


RAID 5
---
3+ drives
Fast reads, OK writes, small files can be slow
Offers ok safety, if a drive fails, you lose nothing
3x 1TB drives = 2TB of storage, you lose 1 drive of space
You need a raid controller card, onboard RAID 5 is slow.

[Leionaaad]

yeah. thanks. i was stupid. I should have read up a bit more.

[Leionaaad]

Ok...can I change now from raid 0 to raid 5(let's say I buy another hdd next month)?? or I will lose everything??

[olson]

Ok...can I change now from raid 0 to raid 5(let's say I buy another hdd next month)?? or I will lose everything??

Some higher end disk controllers will allow online expansion and migration, but most middle controllers won't have that capability, and none of the motherboard controllers will. Chances are you'll have to delete the array and create a new one with the additional disk. Cheers!

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