RAID 5 Windows 10 Host OS Running CentOS-Linux in VirtualBox

Oct 9, 2018
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This is my first time using a Virtual Machine so please forgive my ignorance.

My computer is running Windows 10 and then in VirtualBox I'm running CentOS. I have 3 new 1TB HDDs. I want to run the 3 drives in a RAID 5 configuration and then use the RAID 5 in CentOS. If I setup a RAID 5 in Windows 10 (the host OS) will CentOS recognize the RAID 5?

Or do I need to setup the RAID 5 in my VM? If I'm running RAID 5 in my VM can I also access those drives directly through my host OS (Windows 10)?
 
Solution

USAFRet

Titan
Moderator


Yes, you'd need to set that up inside the VM and the guest OS, Centos.

Aside from just practice and familiarity, I'm unsure of the reasoning behind this config, though.
The CentOS VM is still just a file within host drive system.
 
Oct 9, 2018
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Hi USAFRet, thank you for your response. I wanted to clarify your response.

Yes, if you setup a RAID 5 in Windows 10 that drive will be available for use in CentOS running in VirtualBox. For example, lets say I install three new drives (lets call them drives 2, 3, and 4) and I configure them into a RAID 5, calling it Local Disk (B: ). If I then create a new virtual machine in VirtualBox (for running CentOS), I can select that new Local Disk (B: ) as my storage location. There is no special configuration required for VirtualBox/CentOS to use the RAID 5 drive.

USAFRet, I don't understand your comment regarding being "unsure of the reasoning behind this config." My application for CentOS is to run a server for large file storage. I also need Windows 10 on this same computer to use other software (only compatible with Windows 10). I need the ability to continue running the CentOS server on this computer while simultaneously running Windows 10. In other words, it is not acceptable for me to shutdown my server every time I want to work in Windows (I don't want any server downtime). The only solution to make that possible is to run a virtual machine in a host OS. I wanted to run this server on a RAID 5 drive for all of the normal advantages of RAID 5 (efficient storage, security, performance, etc.).
 

USAFRet

Titan
Moderator


Yes, but it will not be seen as a RAID 5 within the CentOS guest system. It will simply be seen as a single large volume.
Losing any potential benefit of the RAID 5 for the guest OS.

The host Windows would be the only thing that sees the RAID 5.
Sure you can do it that way if you choose.

From your initial comment of "and then use the RAID 5 in CentOS", that did not seem what you wanted the end state to be.
I thought you wanted CentOS to be the RAID controller device.
 
Solution
Oct 9, 2018
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I see, so CentOS will use the RAID 5 (created in Windows 10) as if it were a single drive. I was thinking CentOS would see it as one drive but then Windows 10 (being the RAID controller device) would do the work of creating the disk striping and parity data for anything being saved to that drive.

So if I understand conceptually, (using the example from before with the three drives 2, 3, and 4 making up the RAID 5 drive (B: )) CentOS will do something like save to Drive 2 (until it is full), then move on the Drive 3, and lastly Drive 4; and neither CentOS or Windows 10 will be creating the striping or parity data?

For what I want to do, I will need to leave the three drives (2, 3, and 4 in our example) as individual drives in Windows 10. Then in VirtualBox I will need to create a virtual machine on my boot drive. Then (in VirtualBox) I go into the settings for that VM and in the Controller: SATA (in the Storage tab) I need to add three virtual drives (of the same size), each on a separate physical HDD (in our example one would be created on drive 2, one on drive 3, and one on drive 4). Then I would need to start the virtual machine (running CentOS) and configure the three virtual drives into a RAID 5 configuration in CentOS.

USAFRet, again I appreciate all of your input. Does the above sound accurate? Is there a way for me to add the actual drives to the VM in VirtualBox instead of virtual drives? I don't know that it would make a difference but I want to avoid any risk of saving something onto those drives in Windows 10.
 

USAFRet

Titan
Moderator
Slightly different, but RAID 5->not RAID 5.

My Qnap NAS box is 4 x 4TB drives, RAID 5.
My Windows boxes access that with a simply mapped drive letter. It is imply seen as a single large volume. The desktops neither know nor care what the Linux NAS is doing with its drives.
I'd expect your VM situation would be similar. The guest CentOS just sees whatever volume or "drive" you point it at. The fact that some other system (the host Win 10) is doing the RAID 5 management means nothing to it.

But, I expect that you'd lose the benefits of the RAID 5 within the CentOS world. It is not doing any striping or parity.
I'd have to actually test that concept before trusting it to survive through a drive removal, as is OK in a normal RAID 5.