Skip to main content


Describes members of each mirror the instance is a member of.


[MapMirrors]    Name=,AgentAddress,AgentPort,-,SuperServerAddress,GUID,InstanceDirectory,MemberType,MirrorPrivate,MirrorSSPort,-,EncryptCommunication,


Each entry consists of comma-separated values that define a mirror member. From left to right:

  • Name – Required. Unique name identifying this member within the mirror. An uppercase alphanumeric string with a maximum length of 15 characters, cannot contain spaces or tabs, commas (,), semicolons (;), or equal signs (=), and is converted to uppercase before saving.

    This is the name of this instance in the mirror. Mirror system names must be unique (enforced by the EMS) across all of the mirrors which the EMS manages as an instance has a single mirror system name which may appear in multiple mirror sets (that is, an async member may connect to multiple mirrors). For the most part the GUID is used to identify a mirror member, the Name is used for display purposes. The name cannot contain a colon (:) .

  • AgentAddress – The network address (IP address preferred to avoid DNS issues) that mirror members which connect to the primary should use to contact the Agent on this failover member. This is omitted on async members as the agent is not used for mirroring on those systems. This is required on failover members. The agent can transfer journal data so a private address may be desirable here to avoid network congestion.

  • AgentPort – Port # which the agent on this system is configured to listen on. ##class(SYS.Agent).GetApplicationPort() returns the current value if the local agent is active.

  • For internal use.

  • SuperServerAddress – The network address used to connect to the primary by external mirror-aware systems (currently only ECP application servers, although in the future this may extend to other connections). Other mirror members may connect to a member's superserver address for control and monitoring purposes. When a member is primary, an async member attempts to establish its data channel (over which it receives journal data) using this address if the primary’s mirror private address (MirrorPrivate) is not accessible.

  • GUID – Required. An internal GUID, unique to this mirror. Uniquly identifies this node in the mirror. Apart from identifying the nodes, primarily used to identify the instance that owns a particular copy of a mirrored database.

  • InstanceDirectory – The installation directory of the instance (the parent of the mgr directory). Used primarily on failover members to identify the instance to the agent.

  • MemberType – Numeric value indicating the type of mirror member. One of:

    • 0 - Failover member

    • 2 - Async member

  • MirrorPrivate – When this instance is primary, other mirror members use this address to establish the mirror data channel, over which they receive journal data from the primary. Async members fall back to the primary’s superserver address (SuperServerAddress) if they cannot reach it at the mirror private address.

  • MirrorSSPort – SuperServer port for this instance. Used in conjunction with both the MirrorAddress and the ECPAddress by clients establishing connections to this instance.

  • For internal use.

  • For internal use.

  • For internal use.


Each entry is on one line:


Management Portal

On the pages System Administration > Configuration > Mirror Settings > Create a Mirror > Join as Failover (or Join as Async), enter the requested information.

FeedbackOpens in a new tab