Known limitations for Cloud Volumes ONTAP 9.8 in AWS
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The following known limitations are specific to Cloud Volumes ONTAP in Amazon Web Services. Be sure to also review Limitations for Cloud Volumes ONTAP 9.8 in all cloud providers.
HA pairs not supported with AWS Outposts
Single node systems are supported with AWS Outposts but HA pairs aren’t supported at this time.
Flash Cache limitations
C5D and R5D instance types include local NVMe storage, which Cloud Volumes ONTAP uses as Flash Cache. Note the following limitations:
Compression must be disabled on all volumes to take advantage of the Flash Cache performance improvements.
You can choose no storage efficiency when creating a volume from Cloud Manager, or you can create a volume and then disable data compression by using the CLI.
Cache rewarming after a reboot is not supported with Cloud Volumes ONTAP.
False alarms reported by Amazon CloudWatch
Cloud Volumes ONTAP does not release CPUs when idle, so Amazon CloudWatch can report a high CPU warning for the EC2 instance because it sees 100% usage. You can ignore this alarm. The ONTAP statistics command displays the true usage of the CPUs.
Cloud Volumes ONTAP HA pairs do not support immediate storage giveback
After a node reboots, the partner must sync data before it can return the storage. The time that it takes to resync data depends on the amount of data written by clients while the node was down and the data write speed during the time of giveback.