What synchronous SnapMirror is

In the synchronous mode, SnapMirror enables you to replicate data to the destination as soon as it is written to the source volume.

Synchronous SnapMirror is a feature of SnapMirror. You can use synchronous SnapMirror to replicate data between single storage systems, or storage systems in an active/active configuration, situated at remote sites, using either an IP or a Fibre Channel connection.

In addition to a standard SnapMirror license, the synchronous SnapMirror feature requires a separate license key. You must enter this key and receive important product information prior to enabling the synchronous SnapMirror feature. To enable the synchronous SnapMirror feature, use the license add command.

• How SnapMirror replicates data synchronously
  Before Data ONTAP saves data to the disk, it collects written data in NVRAM. Then, at a point in time called a consistency point, it sends the data to disk.
• How synchronous SnapMirror handles network issues
  If SnapMirror encounters any network issues that restrict the operation of synchronous replication, SnapMirror goes into the asynchronous mode.
• Guidelines for growing an aggregate
  When increasing the size of an aggregate that contains a synchronous SnapMirror destination volume, you need to follow these guidelines.