Featured Post

YouTube and link library for S2D.dk

2020/01/22

S2D and Extents

S2D and Extents Part 1 and 2 - How small a vDisk can you create

*** Disclaimer ***
s2d.dk is not responsible for any errors, or for the results obtained from the use of this information on s2d.dk. All information in this site is provided as "draft notes" and "as is", with no guarantee of completeness, accuracy, timeliness or of the results obtained from the use of this information. Always test in a lab setup, before use any of the information in production environment.
For any reference links to other websites we encourages you to read the privacy statements of the third-party websites.
The names of actual companies and products mentioned herein may be the trademarks of their respective owners.
***

The following Demo is performed in a S2D test environment with 6 Cluster Nodes.

How small a vDisk can you create ?

Part 1




Part 2

The Windows Version is important in this Demo, the Extent size in this Demo is 256MB or 1GB

Each Node have 5 SSDs used for the Storage Pool.

If you don´t have access to physical lab servers you can use WSLab:

Task:
Create the smallest possible vDisk

Columns and Extents:
Know you Columns count and the Extents Size ?

The vDisk is created with the default maximum columns count of 8 and 3 way Mirror


6x5=30 (Host x Disk) the total of physical disks in the Storage pool
3x8=24 
Extents is used (
3 way Mirror x default column count of 8)

Try to create a 1GB vDisk, is that posibel ?
No, Why ?
You have Columns of  8 and each Extents is 1GB so the smallest vDisk will be 8GB (See Video for Part 1)
You have Columns of  8 and each Extents is 256MB so the smallest vDisk will be 2GB (See Video for Part 2)

Windows Server 2016 and Windows Server 2019 (Build: 17763) use a Extents size from 256MB to 1GB in a 3 way Mirror.

Part 1:
The Test "vDisk" was create with the PowerShell command:

New-Volume -StoragePoolFriendlyName S2D* -FriendlyName vDisk1 -FileSystem CSVFS_ReFS -ProvisioningType Fixed -Size 1GB -Verbose

Part 2:
The Test "vDisk" was create with the PowerShell command:

New-Volume -StoragePoolFriendlyName S2D* -FriendlyName vDisk1 -FileSystem CSVFS_ReFS -ProvisioningType Fixed -StorageTierFriendlyNames "Performance" -StorageTierSizes 1GB -Verbose