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MichaelCheathamFIRMINC-0426 avatar image
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MichaelCheathamFIRMINC-0426 asked MichaelCheathamFIRMINC-0426 commented

RAID setup and drive formatting for Hyper-V VHDX (12Gb/s controller and 12Gb/s disks)

I'm configuring a server with 12Gb/s controller and 12 12Gb/s SAS drives (6TB). The purpose of the server is for Hyper-V VHDX file storage. Supermicro LSI SAS 3108 12Gb/s controller. 256GB ECC RAM.

When looking to configure a RAID 10 array, the default strip size for the controller shows 256KB. The Hyper-V host OS will not be installed on this RAID array.
Assuming all 12 drives are used to create one large array, the stripe size would be 1,536KB.

The relationship between the underlying RAID configuration setup and Hyper-V performance is unclear to me.

Since the VHDX files are several hundred GB, is it logical to choose a large strip size yielding a large stripe size?

I've seen contradicting information in researching the topic. Some articles advocate for a 64KB stripe size, others advocate a 64KB strip size, others for a 4KB strip size, and others say to make the stripe size as large as the controller will allow when storing VHDX files.

Some articles point to unused space with large stripe size which would make sense assuming a small file is written to the disk, but this file would be stored inside the large multi-GB fixed disk VM file.

What should be chosen for the strip size and what format should be chosen for the Hyper-V virtual disks inside each VM operating system?
I appreciate your time and any insight.

Michael

windows-server-hyper-v
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LimitlessTechnology-2700 avatar image
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LimitlessTechnology-2700 answered MichaelCheathamFIRMINC-0426 commented

Hello,

Thank you for your question.

As per my experience

The good is to use a 64KB block size for everything, which will ensure the best performance, because when you deal with virtualization you're dealing with large VHD and VHDX files.

On the storage, use 64KB stripe sizes.
Use 64KB cluster size on file system on the host.
Use 64KB cluster size on the file system within the virtual machine.
VHD uses a block size of 2MB and VHDX uses a block size of 32MB, which are both multiples of 64KB. This will provide the best overall performance.



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For the RAID config, are you referring to a 64KB strip or stripe?
A 64KB strip would result in a 384KB stripe with 12 disks in RAID 10.
If it is a 64KB stripe, what strip size would you use to achieve that result?
Thank you for your response.

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