Explanation/Reference:
Host I/O limits is a feature which allows the user to control the amount of throughput and bandwidth consumed by block resources.
This feature can be applied to LUNs, VMFS datastores, or attached snapshots.

When using quotas, administrators have the option to calculate file system usage in one of two ways. This option, which is configured on a per file system basis, may be set to File Size or Block based calculation. When using the default setting of File Size, disk usage is calculated based on logical file sizes in 1K increments.
Because of this, it is possible that used space may be reported from a quota perspective as more than the actual usage if holes exist in a sparse file. This setting is generally recommended for Windows environments.
The Block quota policy calculates disk usage in 8-16KB file system blocks, and is accurate with regard to the actual allocation down to the block level. This setting is recommended for UNIX environments.
Reference: https://www.dellemc.com/en-zm/collaterals/unauth/white-papers/products/storage/h15572-dell- emc-unity-nas-capabilities.pdf

Recovery Point Objective (RPO) is an industry accepted term that indicates the acceptable amount of data, measured in units of time, that may be lost in a failure. When you set up an asynchronous replication session, you can configure automatic synchronization based on the RPO. You can specify an RPO from a minimum of 5 minutes up to a maximum of 1440 minutes (24 hours).
References:
https://www.emc.com/dam/uwaem/documentation/unity-p-replication-config.pdf (page 7)