HyperV Storage SMB SHARE

Sri M
Sri M used Ask the Experts™
Hello Experts,

Need few clarifications in HyperV storage which is an SMB storage. I created a storage space with onboard disks of Win server 2012 R2 with file services installed on it. Its has 8x 1.2 TB drives, 4x 900 GB drives. I selected all these drives and created a storage pool which shows 12 TB as total storage. Now when I am creating a virtual disk in mirror mode it should give me a total of 6 TB approx but when I am creating it just tells I can create a vdisk with maximum size of 4.9 TB instead of 6 TB. When I tried to create second vdisk it shows up the remaining space which is 1.09 TB.

Is there any limitation on creating a virtual disk?

Thanks in advance

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Al faR&D, ITOps Mgr

- Is it an IDE or SCSI disk you are creating?

- What is the cluster size of the container volume in host OS?

- Is the host volume to be shared with other guest OS? Could you consider Pass-Through-ing the host disk to the guest OS?
Technology and Business Process Advisor
Most Valuable Expert 2013
Storage spaces has to use the most common denominator for each array you create.  So, with 8x1200 and 4x900, the largest array you can create is 12x900 which is 10,800 GB.  Then you have to remember that the size of the drives is based on 1 GB = 1,000,000,000 and NOT 1,073,741,824 which is how the computer thinks of 1 GB.  So you're left with 4.9 TB as seen by the computer and assuming you're mirroring.

Once you create that large on, you're left wit 8x300 unused space.  Which is 1.2 TB assuming you mirror,


Appreciate for your replies. Lee I guess your explanation gave me the inputs I am looking for. Thanks a lot..

If I add more 4 HDD of 1.2 TB I should be able to expand the 4.9 TB virtual disk right? or am I again restricted by number of columns Windows allocates for each virtual disk?
Lee W, MVPTechnology and Business Process Advisor
Most Valuable Expert 2013
When using storage spaces, you have to be careful how you allocate things - as you mention columns - If you create a 12 column array, you can only expand it with 12 more columns - you're better off creating it with 4 or 6 columns and expanding it that way.

Check out http://www.miru.ch/why-column-size-does-matter-with-storage-spaces/ and https://blogs.technet.microsoft.com/askpfeplat/2013/09/24/storage-spaces-understanding-storage-pool-expansion/

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