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AFF Partitioning in 9.1

I had such good luck with my last post. I'm going for 2 for 2. Smiley Very Happy


Current Ontap 9 Documentation states that in an AFF, you should assign disks 0-11 to node 1 and 12-24 to node 2. (PG 8)



However, I see that we now have 2 data partitions:


xxxxx::*> disk partition show 9.0.1.*

                          Usable  Container     Container

Partition                 Size    Type          Name              Owner

------------------------- ------- ------------- ----------------- -----------------

9.0.1.P1                   1.72TB spare         Pool0             xxxxx

9.0.1.P2                   1.72TB spare         Pool0             xxxxx

9.0.1.P3                  59.72GB aggregate     /xxxrootxxx/plex0/rg0




Should the new best practice be to assign all P1's to node 1 and all P2's to node 2?



Looking for some guidance.


Thanks in advance!


Re: AFF Partitioning in 9.1

That is correct.


Root-Data-Data (R-D2) partitioning divides SSDs into 2 large data partitions and 1 small root partition. One data partition per SSD is assigned to each node in the HA pair.


Only one SSD is required for hot spare partitions. This results in more usable capacity.


You then create an aggregate with a raid size of 23 (21 data + 2 parity) on each node.


I hope this helps!



Re: AFF Partitioning in 9.1

The extra data partition in the root-data-data version doesn't really change the disk assignment guidance for the physical (container) disks in an AFF system.  We're still say saying half of the shelf is owned by node 1 and the other half is owned by node 2. 


See step 9 in this KB:


Re: AFF Partitioning in 9.1

[ Edited ]

Hi Andris, the KB article seems to talk about the advanced disk partitioning with 2 partitions, not the newer enahnced ADP 3 partition layout. I've been looking for some more documentation on the 3 partition layout but can't find any links or sections in the 9.1 documentation. Would you have a KB or documentation link for it ?

Re: AFF Partitioning in 9.1

That's the right KB...


root-data-data = 3 partitions.


Only AFF systems running 9.0+ are supported for root-data-data partitioning.

Re: AFF Partitioning in 9.1

[ Edited ]

Is best practice for 3 partitions root+data+data assigned to the same node, or would you assign 1 data partition to the HA partner, or doesn't it matter ?


FYI - I'm enquiring about A300's running 9.1

Re: AFF Partitioning in 9.1

The container partition (the disk itself) is assigned to one node. The data partitions are assigned to both nodes, so one node owns the root partition and one data partition, while the other node owns the second data partition.


You might want to take a look at Understanding root-data partitioning for additional information.

Re: AFF Partitioning in 9.1

Hi Dirk,


After a re-initialization of the system with 1 shelf the disk assignment is as follows:


Disk Slot: 0 - 11 assigned to node 2

Disk Slot: 12 - 23 assigned to node 1


Disks 0 - 1 partitions 1,2,3 are assigned to node 2 (partition 1 and 2 being data and partition 3 being root)

Disks 12 -23 parititions 1,2,3 are assigned to node 1 (partition 1 and 2 being data and partition 3 being root)


According to the documentation in the "understanding root-data parititioning"  it states:


Root-data-data partitioning creates one small partition as the root partition and two larger, equally sized partitions for data as shown in the following illustration.

Creating two data partitions enables the same solid-state drive (SSD) to be shared between two nodes and two aggregates.


After initialization of the system the 2 data partitions of a disk are not shared amongst nodes.


If I remove ownership of 1 partition and try to assign the disk to the opposite node, the system does not allow me:


Node1> disk show -n
DISK                OWNER
------------          ------------- 
0b.00.23P2     Not Owned 


Node1> disk assign 0b.00.23P2
disk assign: Cannot assign "0b.00.23P2" from this node. Try the command again on node Node2

Re: AFF Partitioning in 9.1

I had a support ticket open along side these posts which pointed me in the right direction. Finally got to the bottom of it if and hopefully helps out some people:


So from the factory or from a complete system re-initialization a node will own all data partitions of a disk, P1, P2 and P3.


If you want to set it up like in the documentation where you assign P2 to the opposite node, you have to do the following:


1. make sure the disk is listed as a spare. ::> storage aggregate show-spare-disks

2. enter advanced mode ::> priv set adv

3. To assign data P2 to the opposite node, in this case Node2. ::>storage disk assign -disk 2.0.0 -owner Node2 -data2 true -force true (use -data1 if you wish to reassign data1 partition)


FYI - On a 3.8TB SSD you will see around 1.74TB per data partition.

Re: AFF Partitioning in 9.1

Hello everyone,


I want to ask a different question, how can we add 8 SSD to an existing AFF8040 which has 40 parition SSD?