Disks and aggregates
Understanding how Cloud Volumes ONTAP uses cloud storage can help you understand your storage costs.
|All disks and aggregates must be created and deleted directly from Cloud Manager. You should not perform these actions from another management tool. Doing so can impact system stability, hamper the ability to add disks in the future, and potentially generate redundant cloud provider fees.|
Cloud Volumes ONTAP uses cloud provider storage as disks and groups them into one or more aggregates. Aggregates provide storage to one or more volumes.
Several types of cloud disks are supported. You choose the disk type when you create a volume and the default disk size when you deploy Cloud Volumes ONTAP.
|The total amount of storage purchased from a cloud provider is the raw capacity. The usable capacity is less because approximately 12 to 14 percent is overhead that is reserved for Cloud Volumes ONTAP use. For example, if Cloud Manager creates a 500 GiB aggregate, the usable capacity is 442.94 GiB.|
In AWS, Cloud Volumes ONTAP uses EBS storage for user data and local NVMe storage as Flash Cache on some EC2 instance types.
- EBS storage
In AWS, an aggregate can contain up to 6 disks that are all the same size. The maximum disk size is 16 TiB.
The underlying EBS disk type can be either General Purpose SSDs (gp3 or gp2), Provisioned IOPS SSD (io1), or Throughput Optimized HDD (st1). You can pair an EBS disk with Amazon S3 to tier inactive data to low-cost object storage.
Tiering data to object storage is not recommended when using Throughput Optimized HDDs (st1).
- Local NVMe storage
Some EC2 instance types include local NVMe storage, which Cloud Volumes ONTAP uses as Flash Cache.
In Azure, an aggregate can contain up to 12 disks that are all the same size. The disk type and maximum disk size depends on whether you use a single node system or an HA pair:
- Single node systems
Single node systems can use three types of Azure Managed Disks:
Premium SSD Managed Disks provide high performance for I/O-intensive workloads at a higher cost.
Standard SSD Managed Disks provide consistent performance for workloads that require low IOPS.
Standard HDD Managed Disks are a good choice if you don’t need high IOPS and want to reduce your costs.
Each managed disk type has a maximum disk size of 32 TiB.
You can pair a managed disk with Azure Blob storage to tier inactive data to low-cost object storage.
- HA pairs
HA pairs use Premium page blobs, which have a maximum disk size of 8 TiB.
Google Cloud storage
In Google Cloud, an aggregate can contain up to 6 disks that are all the same size. The maximum disk size is 64 TiB.
The disk type can be either Zonal SSD persistent disks, Zonal Balanced persistent disks, or Zonal standard persistent disks. You can pair persistent disks with a Google Storage bucket to tier inactive data to low-cost object storage.
The RAID type for each Cloud Volumes ONTAP aggregate is RAID0 (striping). Cloud Volumes ONTAP relies on the cloud provider for disk availability and durability. No other RAID types are supported.
RAID0 doesn’t support the use of hot spares for redundancy.
Creating unused disks (hot spares) attached to a Cloud Volumes ONTAP instance is an unnecessary expense and may prevent provisioning additional space as needed. Therefore, it’s not recommended.