An ONTAP FlexGroup volume is a scale-out NAS container that provides high performance along with automatic load distribution and scalability. A FlexGroup volume can provision a massive single namespace using the entire cluster resources. While a FlexVol volume is limited by the maximum of 100TB, a FlexGroup can grow up to 20PB.
Starting from Xena release, NetApp ONTAP driver has been supporting provision and manage FlexGroup shares. The driver reports an specific pool for FlexGroup purpose. In other words, before Xena all NetApp ONTAP pools provision share as FlexVol, with Xena release, the pool is either for FlexGroup or FlexVol provisioning, depending on the setup.
The main difference of the pool styles is the aggregate view: while the FlexVol is resided on one of the cluster’s aggregates, the FlexGroup may be resided on several aggregates in the same cluster.
To maintain the compatibility with previous releases, the FlexVol pools continue to be reported even with FlexGroup setup. By default, the FlexVol and FlexGroup pools will work together in the same backend. However, the driver also supports standalone FlexGroup pools configuration.
Important
The FlexGroup feature requires ONTAP 9.8 or newer.
Important
Migration to another pools is not supported;
Migration of share server containing FlexGroup shares is not allowed;
Consistency group is not supported;
Replication with more than one non-active replica is only allowed with ONTAP 9.9.1 or newer.
The utilization metric is currently unsupported for FlexGroup
pools and is not calculated. It’s value is always set to 50 by
default.
Warning
Configuring FlexGroup pool drops the consistency group support for the entire backend. Therefore, if consistency groups are being used or will be required in the future, FlexGroup pools must not be configured in the backend, because even the FlexVol pools would lose its support.
The FlexGroup pool is not enabled by default, the administrator has to
configure the manila.conf. There are two modes: auto provisioning pool or
custom pool.
The easiest and recommended way to configure the FlexGroup is by using the
auto-provisioning mode. In this mode, the driver will report a single pool
named as flexgroup_auto that represents the entire cluster’s aggregates
(or SVM). In case the scheduler chooses that pool, the ONTAP will select in
which set of aggregates the share will be provisioned based on its own
algorithm. The operator has no control of the aggregate selection for the
FlexGroup share.
Note
ONTAP selects two aggregates with the largest amount of usable space on each node to create the FlexGroup volume. If two aggregates are not available, ONTAP selects one aggregate per node to create the FlexGroup share.
To start working with auto-provisioning FlexGroup, add to the backend
configuration the option netapp_enable_flexgroup as True.
If desired, the driver can control the set of aggregates where the FlexGroup share is created. Instead of relying on ONTAP selection, the administrator can manually configure the FlexGroup pools, informing their names and their list of aggregates.
To start working with custom FlexGroup pool, add to the backend configuration
the options netapp_enable_flexgroup as True together with
netapp_flexgroup_pools with the FlexGroup pools (name and list of
aggregates). Example of a backend:
[cdotWithFlexGroup]
share_backend_name = cdotWithFlexGroup
...
netapp_enable_flexgroup = True
netapp_flexgroup_pools = fg1: aggr1 aggr2, fg2: aggr2 aggr3
...
In this example, the backend cdotWithFlexGroup will report two FlexGroup
pools: fg1 that is over aggr1 and aggr2 and pool fg2 that is
over aggr2 and aggr3. So, if the scheduler selected, for instance, the
pool fg1, the created share will be a FlexGroup volume on aggr1 and
aggr2.
To work with standalone FlexGroup pools, in the backend with FlexGroup
configuration (either auto-provisioning or custom one), add the configuration
option netapp_flexgroup_pool_only as True.
Caution
Enabling this option will make the driver stop reporting the FlexVol pools. Make sure that the backend has no FlexVol shares, otherwise those shares may not be managed by Manila anymore.
This document is licensed under Apache 2.0 license.