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I have an interesting RAID setup across 2 harddrives on my home computer. I have /tmp and a mount point(/home/machines) for virtual machines (along with a few other mount points). These partitions I consider replaceable, so I put them on RAID 0 for speed and extra space. If a harddrive was to crash, I'd have to spend a lot of time reinstalling things, but I wouldn't lose things I did RAID-1 on such as /home. I can definitely tell a performance increase from having the virtual harddrives in a RAID-0 setup. Booting Windows XP in a virtual machine in 8 seconds is just beautiful.

Now, I'm looking at if I should buy another (identical) harddrive or two for either extending my RAID-0 portion, or turning it into RAID 0+1. For virtual machines, speed is my only concern. Everything in virtual machines is just a reinstall away.

I understand that RAID-0 is the fastest, yet most dangerous RAID. However, at what point does the SATA controller get maxed out and RAID 0 doesn't give a performance benefit? If I don't get a performance benefit, then I'd rather go RAID 0+1. However, if I can get a benefit, I'll go RAID-0 because I'll do anything to make virtual machines faster(except for buy expensive SSDs :P)

So basically, at what point does RAID-0 not give a performance benefit and instead just be a risky practice?

My motherboard has 8 SATA-III ports and the harddrives I use are 500G WD Black, 6 Gbit/s, 64M cache. (which I consider very fast without RAID even). I use the XFS filesystem

What I'm looking for are some general guidelines. Like for IDE drives, I know that basically bandwidth is split between two drives on the same controller. My question comes to a point as to when will I probably saturate the link, and is there any bandwidth sharing for SATA ports like there is for IDE?

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closed as not constructive by RedGrittyBrick, BBlake, Randolph West, Dave M, Ƭᴇcʜιᴇ007 Sep 25 '12 at 17:13

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Isn't the answer likely to depend on the specific make & model of both controller and disks and therefore be of no use to anyone else? –  RedGrittyBrick Sep 25 '12 at 16:05
    
It also depends on how much you value your data. If you're just running a VM that gets backed up regularly, you might not worry much about the risks associated with one of the drives going bad. –  JW8 Sep 25 '12 at 16:08
    
Well, I'm fine with reinstalling the VMs from scratch. It'll just be a day lost. they have no critical data –  Earlz Sep 25 '12 at 16:11
    
@RedGrittyBrick Not necessarily, I'm sure there are some guidelines even if it does depend on specifics. Like for IDE drives, I know that basically bandwidth was split between two drives on the same controller. My question comes to a point as to when will I probably saturate the link, and is there any bandwidth sharing for SATA –  Earlz Sep 25 '12 at 16:13
    
With two 6GBps channels, what makes you think you're going to saturate the link? –  user3463 Sep 25 '12 at 16:25