Need help with raid

[gentoonewb39]

I want to set up a raid server but I have several questions, my hardware will be 3*160gb + 1*200gb drives.

1.I read that setting it to raid 0 is very dangerous and that one should set it to raid 5 but how dangerous is it really and how much storage space will be lost in raid 5 compared to raid 0.

2.The 200gb drive is allready full to the brim and I found this soulution to be able to add it to the raid will it work?

[skwang]

gentoonewb39,

I can help answering some of your questions.

Question 1:
PC Guide has a great section on RAID arrays that I suggest you read. This link is for the summary comparison of RAID levels which includes handy formulas for computing how much space you will get if you use all four disks in a RAID level 0 or level 5. Note that these are the same for a hardware or software RAID.

Question 2:
This sounds very risky to me.

Question 3:
As per the URL above, it is the smallest disk which limits RAID capacity.

Question 4:
I don't think so. This is especially true with RAID level 1 (simply mirroring) which is what I use. As with RAID level 5 my guess is that you can't just add another disk because how the parity information is stored.

Question 5:
Software RAIDs are in general slower and more resource consuming. I would say if you can get linux drivers for a hardware RAID chip/card, go with the hardware RAID. Again, PC Guide has a page on this; there is a link at the bottom with qualities for software RAIDS.

Two recommendations. High Point Technologies sells PCI RAID controllers. They also release binary closed-source linux drivers for their RAID controllers which is good. You may have to fiddle with the kernel to get it to work, as I did. I purchased one two years ago and have been running a RAID 0 and a RAID 1 (separately) for a while. The RAID 0 is for speed and the RAID 1 is for some redundency.

The second recommendation is that you put the three 160GBi disks into a RAID 5 which is pretty fast and has redundency. This will give you 320GBi of space which equals about 300 GB of real HD space (base two as oppose to base 10). Copy over all your "essential" data, things that you want to have reducency for to your RAID. Keep the 200GBi disk out of the RAID and use it for your "base" HDD. Software goes onto the 200GBi disk while data goes onto the RAID. If the 200GBi disk fails you can always reinstall the software. While your data is protected because it is on a RAID.

Lastly, although your data is on a RAID that does not mean you should ignore making backups! Still back up your data to CDs or DVDs.

--Shawn