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ONTAP creates an aggregate with twice the number of specified disks with ADPv2

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Applies to

ONTAP 9

AFF Systems

Answer

When an HA system is initialized with more that (24) physical disks (also known as ‘container’ disks here) ONTAP will partition all of the disks, then assign all of the P1/P2 data partitions of half of the total number of disks to the first node and the remaining half to the second node.

Example:

Node_A with HA partner Node_B has (2) fully populated (24) disk shelves, for a total of (48) container disks. 

As the nodes now own both the P1 and P2 data partitions for their respective container disks, when you create a data aggregate and specify the disk count

cluster_CLI::> storage aggregate create -aggregate aggr1_ssd_1 -node Node_a -diskcount 22 

ONTAP will create the aggregate with (2) RAID groups (RG) of (22) partitions each. RG0 is made up of the P1 data partitions and RG1 is made up of the P2 data partitions:

Aggregate aggr1_ssd_1 (online, raid_dp, fast zeroed) (block checksums)
  Plex /aggr1_ssd_1/plex0 (online, normal, active, pool0)
    RAID group /bond11_ssd_1/plex0/rg0 (normal, block checksums)

      RAID Disk	Device  	HA  SHELF BAY CHAN Pool Type  RPM  Used (MB/blks)    Phys (MB/blks)
      ---------	------  	------------- ---- ---- ---- ----- --------------    --------------
      dparity 	0a.00.0P1	0a    0   0   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      parity  	0d.01.0P1	0d    1   0   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.1P1	0a    0   1   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.1P1	0d    1   1   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.2P1	0a    0   2   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.2P1	0d    1   2   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.3P1	0a    0   3   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.3P1	0d    1   3   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.4P1	0a    0   4   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.4P1	0d    1   4   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.5P1	0a    0   5   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.5P1	0d    1   5   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.6P1	0a    0   6   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.6P1	0d    1   6   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.7P1	0a    0   7   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.7P1	0d    1   7   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.8P1	0a    0   8   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.8P1	0d    1   8   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.9P1	0a    0   9   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.9P1	0d    1   9   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.10P1	0a    0   10  SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.10P1	0d    1   10  SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
            
    RAID group /aggr1_ssd_1/plex0/rg1 (normal, block checksums)

      RAID Disk	Device  	HA  SHELF BAY CHAN Pool Type  RPM  Used (MB/blks)    Phys (MB/blks)
      ---------	------  	------------- ---- ---- ---- ----- --------------    --------------
      dparity 	0a.00.0P2	0a    0   0   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      parity  	0d.01.0P2	0d    1   0   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.1P2	0a    0   1   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.1P2	0d    1   1   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.2P2	0a    0   2   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.2P2	0d    1   2   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.3P2	0a    0   3   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.3P2	0d    1   3   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.4P2	0a    0   4   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.4P2	0d    1   4   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.5P2	0a    0   5   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.5P2	0d    1   5   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.6P2	0a    0   6   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.6P2	0d    1   6   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.7P2	0a    0   7   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.7P2	0d    1   7   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.8P2	0a    0   8   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.8P2	0d    1   8   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.9P2	0a    0   9   SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.9P2	0d    1   9   SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0a.00.10P2	0a    0   10  SA:B   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)
      data    	0d.01.10P2	0d    1   10  SA:A   0   SSD   N/A 7320700/14992794624 7320708/14992811008 (fast zeroed)

This is working as designed and not due to any bug or other inconsistency on the hardware or ONTAP.

The same results would be expected using ONTAP System Manager to create the data aggregate.

Additional Information

If a system is initialized with (24) or less container disks, the default is for Node_A to own the P1 data partitions and Node_B to own the P2 data partitions.