Flexgroup, Infinite volume and Flexvol

Introduced:

Flexvol             -> In Data Ontap 7 [2005]
Infinite vol        -> In Data Ontap 8.1.1 [2012]
Flexgroup vol   -> In ONTAP 9.1 [2017]

Capacity:
Flexvol: A Flexvol can serve up to 2 billion files to a maximum capacity of 100TB.
Infinite Volume: An Infinite Volume can serve up to 2 billion files to a maximum capacity of 20PB.
Flexgroup vol: A Flexgroup Volume can serve up to 400 billion files to a maximum capacity of 20PB.

Nice to know :Maximum number of constituents for a FlexGroup is 200. Since the max Flexvol [basic unit] volume size is 100TB and the max file count for each volume is 2 billion, simple maths gives this figure : 200 x 100TB = 20PB, 200 x 2 = 400 billion files.

Physical bondage:
Flexvol            : Tied to single aggregate and a single node.
Infinite vol      : Tied to multiple aggregates on multiple nodes.
Flexgroup vol : Tied to multiple aggregates on multiple nodes.

Limitation:
Flexvol       : 100TB max size [single Flexvol] - Single Namespace Metadata per Volume
Infinite vol  : 20PB  max size [single Flexvol] - Single Namespace Metadata per Volume
Flexgroup vol  :  20PB  max size [Multiple Flexvols joined together] - No such limitation

Snapshot:
Flexvol:              :Single Snapshot copy across the volume.
Infinite Volume  :Single Snapshot copy that runs across a single large-capacity container.
Flexgroup vol     : Multiple Snapshot copy taken at the same time [All or fail] across a single large-capacity container.

Best suited workloads:
Flexvol: For most use cases, FlexVols are perfect.
Infinite Volume: Best suited for Workloads that are write once, update rarely, with an average file size >100KB [Non-sensitive latency workloads]
Flexgroup vol: Best suited for workloads that are heavy on ingest (a high level of new data creation), heavily concurrent, and evenly distributed among subdirectories.

How to create FlexGroup in ONTAP 9.1

ONTAP9::> flexgroup deploy -vserver CIFS_FG -size 10G -type RW -space-guarantee volume -foreground true -volume FG_CIFS

Warning: FlexGroup deploy will perform the following tasks:

 The FlexGroup "FG_CIFS" will be created with the following number of constituents of size 640MB: 16. The constituents will be created on the following aggregates:

aggr0_ONTAP9_01_DATA1
aggr0_ONTAP9_01_DATA2
aggr0_ONTAP9_02_DATA1
aggr0_ONTAP9_02_DATA2

Do you want to continue? {y|n}: y

[Job 62] Job succeeded: The FlexGroup "FG_CIFS" was successfully created on Vserver "CIFS_FG" and the following aggregates: aggr0_ONTAP9_01_DATA1,aggr0_ONTAP9_01_DATA2,aggr0_ONTAP9_02_DATA1,aggr0_ONTAP9_02_DATA2

ONTAP9::>

Observation:

This is a 2-Node SIMBOX Cluster. Looks like In order to create a FlexGroup, each NODE requires minimum '2' DATA Aggregates, so total 4 for 2 Node Cluster.

In this example, I created a FlexGroup of Volume Size 10G, and ONTAP automatically divided 10G in 16 CHUNKS of 640MB => 16 x 640 = 10240MB = 10GB.

It appears that FG requires:

1. Minimum 2 Data aggregates on each Node.
2. It Divides the volume[whatever] size in 16 CHUNKS, 4 in each of the aggregate.

I.e. 10G / 4 = 2.5 GB on each aggregate.

For more info:

Flexgroup volume  :http://www.netapp.com/us/media/tr-4557.pdf

Infinite volume      :https://www.netapp.com/us/media/tr-4037.pdf

Flexvol volume     :https://www.netapp.com/us/media/tr-3356.pdf