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RAID 0 inside a virtual machine

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November 10, 2011 1:06:41 PM

Hi I'm want to take two virtual hard drive files each located in a separate hard drive and have them raided inside a virtual machine. I don't want to raid the physical hard drives, just the virtual hard drives inside the virtual machine. That way I can move the machine to other computers without needing too set them up in raid.

The virtual machine program is preferably virtualbox but I'll use vmware if necessary.

I have two SATA disks, one 80GB and one 250GB. Both would have a 32GB virtual HDD file and inside the virtual machine they would be used with raid 0. I have windows XP Home x86, XP Pro x86, Vista Home Premium x86, 7 Ultimate x 86 and x64, and any free Linux to use as host and/or guest operating systems.

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November 10, 2011 6:22:35 PM

Are you trying to boost the virtual disk performance?

What you propose might work, but it is unlikely it will give you the boost you expect. Even assuming the virtual cluster size exactly matched the physical cluster size, and the virtual clusters were not misaligned with the physical clusters, you still have a virtual RAID controller slowing down disc access.
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November 10, 2011 6:24:18 PM

Yes I want to improve virtual disk performance. If virtual raid 0 won't work is there any other way to improve the speed considerably?
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November 10, 2011 6:27:19 PM

Also consider that I won't have these two disks being used by the host machine for anything besides the virtual machine.
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November 10, 2011 6:49:39 PM

You could run the VM from an SSD.
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November 10, 2011 6:59:43 PM

I don't have any money to spend and probably won't for a while so I'm stuck with what I have.
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November 10, 2011 10:53:18 PM

You can try your original suggestion, and I would be interested to know how much of a performance boost you get.
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November 10, 2011 11:49:47 PM

I apologize if I sounded more experienced than I am because I don't know how to set up the raid system. I have never used RAID and would be thankful for instructions on how to go about this.
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November 10, 2011 11:57:57 PM

I'm asking this right now because what I have are two 6-8 year old SATA 150 drives that tend to max out around 60-70MB/s each. If I could get a raid system going for the virtual machine only (I want to keep the host without raid because if a hard drive fails in a raid 0 setup its my understanding that you're screwed) then I could get decent performance comparable to a newer hard drive.
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November 13, 2011 3:22:23 AM

You will need to use software RAID, and AFAIK only a Linux guest supports software RAID 0.
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November 13, 2011 3:29:12 AM

Windows 7 ultimate/enterprise/professional all support hardware raid 0 and 1. Windows servers also support dynamic raid 5. Thanks, I'll just google how to setup the software raid 0 and I should be fine.

I'll post how it goes and maybe a few benchmarks if successful.
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November 30, 2011 4:00:45 PM

I apologize for taking so long to get back too this but I am about to attempt this and will post results within an hour or two.
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November 30, 2011 4:45:14 PM

Well I'll have to apologize again but my computer has decided to stop working. I'll trouble shoot and see if I can get it running again. I had no problems at all and no indication of failure before it happened (not even a BSOD) it just failed to boot after I restarted. I assume the hard drives are having some problems on account of them both being 6+ years old.

Before the failure I had my VM running with software RAID 0 without any problems. I'll probably be able to try again later today or tomorrow.
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December 2, 2011 4:52:00 AM

I re-installed my operating system twice but it failed shortly after each install. I tried a different OS and it still failed a few hours after installation. I have just acquired another two hard drives from friends to replace the current set. Unfortunately neither are new but they both have great track records so far and I'll get around to testing either later today (Friday) or this Sunday. If another failure occurs I will close this thread and open a new one when I get money for new hard drives.

I can honestly say that there is a great performance increase from dedicating 12GiB of your RAM (I have 16 total) as a container for a VM's main drive (I watched a VM install server 2008r2 in a few minutes several times, it beats waiting). This only gives great random access time in Virtualbox (I usually use Virtualbox, occasionally VMWare) and not throughput increase because it is a virtual SATA drive and is limited to SATA 2.0 (300MB/s) speeds inside the VM. Because of this I assume that RAID 0 would only give throughput increase until SATA 2.0 bottlenecks the VM's disk throughput. Of course nearing 300MB/s (as measured by Sandra) isn't slow, it's several times faster than my hard drives can go since they tend to top out around 60MB/s. If I remember correctly Sandra gave me about 0.11 ms random access time.

If Oracle isn't already working on virtual SATA 3.0 I will give a hint. Or better yet any virtual interface that would outpace SATA 3.0, maybe virtual 8Gb fiber channel or something like that.
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December 12, 2011 5:23:33 AM

Best answer selected by blazorthon.
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December 12, 2011 5:39:59 AM

This topic has been closed by Nikorr.
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