Qs about RAID0 & expandability

I'm planning a new computer, and one requirement is high storage. the current idea is revolving around using a RAID0 array of 4*160 drives, but after digging through overclocker's products, I'm coming out a little confused.

nothing I could find there seems to be able to support > 2 SATA drives in RAID, they're all ATA 133:

1) is this just a limit to practical RAIDs that I wasn't aware of

2) what kinda performance hit would I expect from shifting from SATA drives to ATA 133?

3)If 4 drive SATA RAIDs are around (and not at silly prices), can anyone point me to somewhere I can get them from? (In the UK)

4) I'm also currently planning on using onboard RAID controllers, such as the ASUS P4P800 Deluxe "springdale" board, this shouldn't be any better/worse than grabbing a PCI controller should it?

5)Also, due to cash issues, I'm probably not going to be able to buy all the drives at once, probably get 2 or 3, then add the rest at a later date, but I'm not sure how easy it would be to expand an existing RAID, I'm guessing adding a new drive would require reformatting the whole array, as it's kinda imittating a single, very large drive, this right?

6) just out of habit, I try to do everything in powers of 2, but is there any disadvantage to using 3 drives, as opposed to 2/4 (I'm guessing with a good controller the answer's no)

7) and on a similar point, how about having different sized drives in the array (bearing in mind this is RAID0, so there's no mirroring going on).

8) finally, anyne know what sort of transfer speeds you're likely to get off a single RAID controller, or is this a massive variable based on # of drives & make on controller?


9)If the 4 drive option is unfeasible, going with 2*250 Maxtor SATAs is the other option, any comments?

Thanks for any help you guys can give, some of this may seem silly, but I wanna be sure exactly what to expect before I go spending a ton of cash.

-mark

1) is this just a limit to practical RAIDs that I wasn't aware of

No. HighPoint makes both four and eight drives PCI RAID controllers:

HighPoint SATA Raid Controllers


2) what kinda performance hit would I expect from shifting from SATA drives to ATA 133?

You probably will experience about the same performance from either setup. My opinion is not much more if any. The maximum bandwidth your going to get from SATA with it's current implementation is 150MB/Sec. That's not much more than the current maximum bandwidth of ATA133.


3)If 4 drive SATA RAIDs are around (and not at silly prices), can anyone point me to somewhere I can get them from? (In the UK)

Visit the above link


4) I'm also currently planning on using onboard RAID controllers, such as the ASUS P4P800 Deluxe "springdale" board, this shouldn't be any better/worse than grabbing a PCI controller should it?

It all depends on how closely the controller circuitry is to the PCI bus in both cases. A number of other variables are at play as well. For example, depending on the general use of the system in day to day operations should determine the block sized used. If your using the system to do a lot of multimedia work where your transferring huge amounts of data, then the block sized should be larger, like 64K. However, if your the average user, then a smaller size is more in line, such as 4K. This value is the amount data, at a minimum, that will be trasferred across the bus. If your not going to be transferring huge amounts of data on a daily basis, then using 64K block sizes is crazy. You'll see a huge performance hit.



5)Also, due to cash issues, I'm probably not going to be able to buy all the drives at once, probably get 2 or 3, then add the rest at a later date, but I'm not sure how easy it would be to expand an existing RAID, I'm guessing adding a new drive would require reformatting the whole array, as it's kinda imittating a single, very large drive, this right?

That is correct. When you add a drive to an existing RAID array, you will need to break the array and then recreate it. In doing so, you WILL lose all your data, so ensure you have some kind of backup plan in place.



6) just out of habit, I try to do everything in powers of 2, but is there any disadvantage to using 3 drives, as opposed to 2/4 (I'm guessing with a good controller the answer's no)

To gain a better understanding of what RAID array is right for you, I suggest checking out the following link:

http://www.ebabble.net/html/types.html



7) and on a similar point, how about having different sized drives in the array (bearing in mind this is RAID0, so there's no mirroring going on).

You can do this, but, your only going to be able to get the maximum of the smallest drive available. Thus, one 40GB and one 20GB drive would only give you an array of 40GB. Only the first 20GB of the 40GB drive will be used.



8) finally, anyne know what sort of transfer speeds you're likely to get off a single RAID controller, or is this a massive variable based on # of drives & make on controller?

AFAIK, you can only have one controller of the the same type in any given system. However, I'm not sure if you mix, for example, SCSI RAID with IDE RAID controllers. Going with any more than 2 drives in a RAID ) array is pointless really. How fast do you really need to go? I had four 80GB drives in RAID 0 for about six months. One of the drives in that failed and I never was able to get my lost data. I highly suggest using a RAID array with some data protection, like RAID 5. However, it is your choice. Since then, I have switched to a three drive RAID 5 array and have one drive in the system on an IDE controller that is used for data backup.

thanks for all that. What you've said & the links look really helpful. Should be able to work out what I really need.

Thanks again
-mark