Replication and Folders

When you create volumes on a downstream partner, you should use a local folder. There are some differences in how folders work with synchronous replication. Folder limit enforcement and synchronous replication are independent. Therefore, you can perform the following actions:

• Associate one or more upstream synchronously-replicated volumes with a folder that has folder limit enforcement
• Associate one or more downstream synchronously-replicated volumes with another folder that has folder limit enforcement

Two folders can have a mix of synchronously-replicated and snapshot-replicated volumes, and folder limits can be set to different values, because each folder is independent of the other.

You can also choose to associate only the upstream or only the downstream volumes with a folder or volumes. It is not possible to associate both upstream and downstream volumes with the same folder, because folders are pool-scoped objects.

Either the upstream or the downstream folder (or both) can reach the folder limit. As part of folder limit enforcement, all the thin provisioned volumes in the folder are either taken offline or made read-only based on the performance policy associated with them.

When an upstream, synchronously-replicated volume is taken offline, additional I/O is not accepted.

When a downstream, synchronously-replicated volume is taken offline or is made read-only, then the upstream volume goes out of sync, but host I/O is accepted. Note that I/O resynchronization is continuously attempted by the upstream volume in this state.