n is either 1 or 0.
AsyncMemberType indicates how the reporting async member purges mirror journal files received from the primary failover member.
For more information, see the Editing or Removing an Async Members section of the chapter “Mirroring” in the High Availability Guide.
Changing This Parameter
On the Edit Async page of the Management Portal (System Administration > Configuration > Mirror Settings > Edit Async), for a reporting async member, use the Mirror Journal File Retention drop-down to determine how mirror journal files are purged.
Instead of using the Management Portal, you can change AsyncUseSystemPurgeInterval in the Config.MirrorMemberOpens in a new tab class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).