Understanding how Cloud Volumes ONTAP uses cloud storage can help you understand your storage costs.
Cloud Volumes ONTAP uses AWS and Azure volumes as back-end storage. It sees these volumes 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 creating volumes and the default disk size when you deploy Cloud Volumes ONTAP.
|The total amount of storage purchased from AWS or Azure 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 GB aggregate, the usable capacity is 442.94 GB.|
In AWS, an aggregate can contain up to 6 disks, with a maximum disk size of 16 TB. The underlying EBS disk type can be either General Purpose SSD, Provisioned IOPS SSD, Throughput Optimized HDD, or Cold HDD. You can also pair an EBS disk with Amazon S3 for data tiering.
At a high level, the differences between EBS disk types are as follows:
General Purpose SSD disks balance cost and performance for a broad range of workloads. Performance is defined in terms of IOPS.
Provisioned IOPS SSD disks are for critical applications that require the highest performance at a higher cost.
Throughput Optimized HDD disks are for frequently accessed workloads that require fast and consistent throughput at a lower price.
Cold HDD disks are meant for backups, or infrequently accessed data, because the performance is very low. Like Throughput Optimized HDD disks, performance is defined in terms of throughput.
|Cold HDD disks are not supported with HA configurations and with data tiering.|
For additional details about the use cases for these disks, refer to AWS Documentation: EBS Volume Types.
In Azure, an aggregate can contain up to 12 disks. 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 two types of Azure Managed Disks:
Premium SSD Managed Disks provide high performance for I/O-intensive workloads at a higher cost.
Standard HDD Managed Disks are a good choice if you don’t need high IOPS and want to reduce your costs.
Both disk types have a maximum disk size of 4 TB.
You can pair a managed disk with Azure Blob storage for data tiering.
- HA pairs
HA pairs use Premium page blobs, which have a maximum disk size of 8 TB.
For additional details about the use cases for these disks, see Microsoft Azure Documentation: Introduction to Microsoft Azure Storage.