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Very small size of a Storage Pool consisting of SSDs disks only (31,5 GB of 745GB of each SSD disk is reserved) RRS feed

  • Question

  • Hi,

    I have a problem with the capacity of SSD disks used in the storage pool. I have 4 nodes with Windows Server 2016 TP4 in a failover cluster - each of them has 4 physical SSD disks:

    PS> Get-PhysicalDisk -CanPool $True |? MediaType -eq SSD
    
    FriendlyName               Size
    ------------               ----
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB
    ATA INTEL SSDSC2BB80  745.21 GB

    The problem is that when I create a storage pool, only 31,5 GB of each SSD disk is used (31,5 * 16 = 504GB):

    $PhysicalDisks = Get-StorageSubSystem -FriendlyName '*storage_cluster*' | Get-PhysicalDisk -CanPool $True |? MediaType -eq SSD
    $StoragePool = New-StoragePool -FriendlyName company_data -StorageSubsystemFriendlyName '*storage_cluster*' -PhysicalDisks $PhysicalDisks -ProvisioningTypeDefault Fixed -ResiliencySettingNameDefault Mirror -EnclosureAwareDefault $true
    $PoolSizeGb = $StoragePool.Size / 1024 / 1024 / 1024
    Write-Host "Pool size: " $StoragePool.Size " = " $PoolSizeGb "GB"
    Pool size:  541165879296  =  504 GB

    Adequately:

    PS> Get-PhysicalDisk |? MediaType -eq SSD
    
    FriendlyName              Size
    ------------              ----
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB
    ATA INTEL SSDSC2BB80   31.5 GB

    Anyone has any suggestions? Note that I've done exactly the same with HDD disks (each host had 4 HDD 1TB disks) and the size of newly created storage pool was properly set to ~15TB. 

    Thanks!


    • Edited by mateuszb Thursday, March 17, 2016 11:25 AM Invalid code block
    Thursday, March 17, 2016 11:20 AM

Answers

  • Thank you for the answers. I haven't set either any quota or tiers - I just did the steps pasted in the code blocks.

    I managed to find the right answer - it looks like with Storage Spaces Direct my SSD disks are automatically set as caching devices - leaving only ~32GB of usable storage space on each disk. This is because of the new 'Software Storage Bus Cache' feature:

    https://blogs.technet.microsoft.com/clausjor/2015/11/19/storage-spaces-direct-under-the-hood-with-the-software-storage-bus/ 

    SBC creates a special partition on each caching device that, by default, consumes all available capacity except 32GB. The 32GB is used for storage pool and virtual disk metadata.

    Regards,

    Mateusz

    • Marked as answer by Mary Dong Tuesday, April 5, 2016 1:33 AM
    Friday, March 18, 2016 7:57 AM

All replies

  • Hi

    Did you have been set the tier quota? like the link below

    http://blogs.technet.com/b/enterprise_admin/archive/2013/07/09/tiered-storage-second-step-creating-my-virtual-disk-and-volume.aspx

    Friday, March 18, 2016 7:34 AM
  • Hi mateuszb,

    Thanks for your post.

    You could also add the column number to have a check.

    Please refer to the article for more details

    http://social.technet.microsoft.com/wiki/contents/articles/11382.storage-spaces-frequently-asked-questions-faq.aspx#What_are_columns_and_how_does_Storage_Spaces_decide_how_many_to_use

    Besides, this is the Preview version, there may exist the imperfection for these version, if possible, you could also do the test on other server 2016, if all with the same problem, it mgiht be design. And you might need to wait for a period of time to check if there's some declaration

    Best Regards,

    Mary Dong


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Friday, March 18, 2016 7:47 AM
  • Thank you for the answers. I haven't set either any quota or tiers - I just did the steps pasted in the code blocks.

    I managed to find the right answer - it looks like with Storage Spaces Direct my SSD disks are automatically set as caching devices - leaving only ~32GB of usable storage space on each disk. This is because of the new 'Software Storage Bus Cache' feature:

    https://blogs.technet.microsoft.com/clausjor/2015/11/19/storage-spaces-direct-under-the-hood-with-the-software-storage-bus/ 

    SBC creates a special partition on each caching device that, by default, consumes all available capacity except 32GB. The 32GB is used for storage pool and virtual disk metadata.

    Regards,

    Mateusz

    • Marked as answer by Mary Dong Tuesday, April 5, 2016 1:33 AM
    Friday, March 18, 2016 7:57 AM