RAID with different sized drives and existing data

[tomtheappraiser]

Hi all,

I just got a new laptop with Windows 8 that I am going to use, along with a dock, as my main computer.
My old desktop currently has Windows 7 with 2-2tb hard drives and a 1 TB HD. I also have a 120 GB SSD that I just switched out of my new laptop in order to increase the size of the HD in the laptop.
I was thinking of converting my desktop system to a Linux based server in a RAID 5 or 10. If I do the RAID 5 I was considering using the SSD as the OS drive separated from the 3 other drives that would be in a RAID 5 array.
So, this presents a couple of issues that I was hoping you fine folks might be able to help me out with.
1) I understand that a Raid will only be the size of n x the lowest GB drive. However, I had read on a forum somewhere that somehow you could use that wasted space in a second array, however, there was no further explanation. Is this possible and, if so, how would I go about doing that.
2) I need to keep the data that I currently have on one of the 2TB drives. My configuration right now is that the 1 TB has the OS and programs on it, 1 of the 2-TB drives is my data storage, with the second be used to backup the 1st one.
The problem I see is that, as I understand it, in order to create a RAID, all the disks have to be wiped out. I don't have another 2-TB drive to back up my data on since, the current backup disk will also be part of the array.
3) I could do a RAID 10 since I have 4 drives, but with the smallest drive being the 120 Gig, I don't think it would make sense to do it. However, if the math worked out with the separate arrays, maybe it would work?

Here are my specs:
Gigabyte GA-E7AUM-DS2H
8 GB RAM
2 2-TB Hard Drives (One Seagate, the other Western Digital)
1 1-TB HD (Western Digital)
Planned Linux OS (Either Ubuntu or Amahi?)

Thanks in advance

 

[RealBeast]

Before you do anything backup all your data that you don't want to lose, converting a disk to a storage array usually deletes all existing data. Then spend some time reading up on your choices.

I would not use RAID 10 as it wastes too much drive space.

A better alternative would be to look at FreeNAS as your server and raidz, which is much more robust and not nearly as sensitive to issues as motherboard based RAID 5.

In any case you need another 2TB drive for redundancy unless you want to use only 1TB on the 2TB drives -- and using the remaining 1TB is not worth attempting.

Leave your OS on the SSD and do not include it in an array unless you buy a high end LSI/Adaptec controller that uses the drive as all cache for the array.